Vehicular Rearview Mirror Elements and Assemblies Incorporating These Elements

ABSTRACT

The present invention relates to improved electro-optic rearview mirror elements and assemblies incorporating the same. Area of the effective field of view of the electro-optic mirror element substantially equals to that defined by the outermost perimeter of the element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/478,224, filed Jun. 29, 2006, which is a continuation-in-part of U.S.patent application Ser. No. 11/066,903, filed Feb. 25, 2005, whichclaims priority under 35 U.S.C. §119(e) from U.S. ProvisionalApplication Ser. Nos. 60/614,150, filed Sep. 29, 2004, 60/605,111, filedAug. 27, 2004, and 60/548,472, filed Feb. 27, 2004. The disclosure ofeach of the abovementioned applications is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

Electro-optic rearview mirror elements are becoming more common invehicular applications with regard to both inside and outside, bothdriver's and passenger's side, rearview mirrors. Typical electro-opticelements, when incorporated in vehicular rearview mirror assemblies,will have an effective field of view (as defined by relevant laws, codesand specifications) that is less than the area defined by the perimeterof the element itself. Primarily, the effective field of view islimited, at least in part, by the construction of the element itselfand, or, an associated bezel.

Various attempts have been made to provide an electro-optic elementhaving an effective field of view substantially equal to the areadefined by its perimeter. Assemblies incorporating these elements havealso been proposed.

What is needed is an improved electro-optic mirror element. Improvementsin assemblies incorporating these improved electro-optic mirror elementsare also needed.

SUMMARY OF THE INVENTION

At least one embodiment of the present invention provides improvedelectro-optic mirror elements. A related embodiment has an effectivefield of view area substantially equal to the field of view associatedwith an area defined by the perimeter of the element.

At least one embodiment of the present invention provides improvedassemblies incorporating electro-optic elements. A related embodimenthas an effective field of view area substantially equal to the area ofthe element itself as defined by its outer most perimeter.

Other advantages of the present invention will become apparent whilereading the detailed description of the invention in light of thefigures and appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a controlled vehicle;

FIG. 2 a depicts an assembly incorporating an electro-optic element;

FIG. 2 b depicts an exploded view of an outside rearview mirror;

FIG. 3 depicts an inside rearview mirror assembly incorporating anelectro-optic element;

FIGS. 4 a-c depict a first surface plan view, fourth surface plan viewand section view of an electro-optic element, respectively;

FIG. 4 d depicts a plan view of a fourth surface;

FIG. 4 e depicts a plan view of a second substrate;

FIG. 5 depicts an enlarged view of FIG. 4 c;

FIG. 6 depicts a graph of color-related characteristics for variouselectro-optic element components;

FIGS. 7 a-n depict various techniques for establishing externalelectrical connections to the second and third surface conductiveelectrodes;

FIGS. 8 a-n depict various electrical clips for establishing externalelectrical connections to the second and third surface conductiveelectrodes;

FIGS. 9 a-m depict various views of carrier/bezel assemblies for usewith electro-optic elements in a rearview mirror assembly; and

FIGS. 10 a-c depict various views of an electro-optic element/electricalcircuit board interconnection.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIG. 1, there is shown a controlled vehicle 105having a driver's side outside rearview mirror 110 a, a passenger's sideoutside rearview mirror 110 b and an inside rearview mirror 115. Detailsof these and other features will be described herein. Preferably, thecontrolled vehicle comprises an inside rearview mirror of unitmagnification. Unit magnification mirror, as used herein, means a planeor flat mirror with a reflective surface through which the angularheight and width of an image of an object is equal to the angular heightand width of the object when viewed directly at the same distance withthe exception of flaws that do not exceed normal manufacturingtolerances. A prismatic day-night adjustment rearview mirror wherein atleast one associated position provides unit magnification is consideredherein to be a unit magnification mirror. Preferably, the mirrorprovides a field of view with an included horizontal angle measured fromthe projected eye point of at least 20 degrees and a sufficient verticalangle to provide a view of a level road surface extending to the horizonbeginning at a point not greater than 61 m to the rear of the controlledvehicle when the controlled vehicle is occupied by a driver and fourpassengers or the designated occupant capacity, if less, based on anaverage occupant weight of 68 kg. It should be understood that the lineof sight may be partially obscured by seated occupants or by headrestraints. The location of the driver's eye reference points arepreferably in accordance with regulation or a nominal locationappropriate for any 95th percentile male driver. Preferably, thecontrolled vehicle comprises at least one outside mirror of unitmagnification. Preferably, the outside mirror provides a driver of acontrolled vehicle a view of a level road surface extending to thehorizon from a line, perpendicular to a longitudinal plane tangent tothe driver's side of the controlled vehicle at the widest point,extending 2.4 m out from the tangent plane 10.7 m behind the driver'seyes, with the seat in the rearmost position. It should be understoodthat the line of sight may be partially obscured by rear body or fendercontours of the controlled vehicle. Preferably, the locations of thedriver's eye reference points are in accordance with regulation or anominal location appropriate for any 95th percentile male driver.Preferably, the passenger's side mirror is not obscured by an unwipedportion of a corresponding windshield and is preferably adjustable bytilting in both horizontal and vertical directions from the driver'sseated position. In at least one embodiment, the controlled vehiclecomprises a convex mirror installed on the passenger's side. Preferably,the mirror is configured for adjustment by tilting in both horizontaland vertical directions. Preferably, each outside mirror comprises notless than 126 cm of reflective surface and is located so as to providethe driver a view to the rear along an associated side of the controlledvehicle. Preferably, the average reflectance of any mirror, asdetermined in accordance with SAE Recommended Practice J964, OCT84, isat least 35 percent (40 percent for many European Countries). Inembodiments where the mirror element is capable of multiple reflectancelevels, such as with electro-optic mirror elements in accordance withthe present invention, the minimum reflectance level in the day modeshall be at least 35 (40 when for European use) percent and the minimumreflectance level in the night mode shall be at least 4 percent.

With further reference to FIG. 1, the controlled vehicle 105 maycomprise a variety of exterior lights, such as, headlight assemblies 120a, 120 b; foul conditions lights 130 a, 130 b; front turn signalindicators 135 a, 135 b; taillight assembly 125 a, 125 b; rear turnsignal indicators 126 a, 126 b; rear emergency flashers 127 a, 127 b;backup lights 140 a, 140 b and center high-mounted stop light (CHMSL)145.

As described in detail herein, the controlled vehicle may comprise atleast one control system incorporating various components that provideshared functions with other vehicle equipment. An example of one controlsystem described herein integrates various components associated withautomatic control of the reflectivity of at least one rearview mirrorelement and automatic control of at least one exterior light. Suchsystems may comprise at least one image sensor within a rearview mirror,an A-pillar, a B-pillar, a C-pillar, a CHMSL or elsewhere within or uponthe controlled vehicle. Images acquired, or portions thereof, may beused for automatic vehicle equipment control. The images, or portionsthereof, may alternatively, or additionally, be displayed on one or moredisplays. At least one display may be covertly positioned behind atransflective, or at least partially transmissive, electro-opticelement. A common controller may be configured to generate at least onemirror element drive signal and at least one other equipment controlsignal.

Turning now to FIGS. 2 a and 2 b, various components of an outsiderearview mirror assembly 210 a, 210 b are depicted. As described indetail herein, an electro-optic mirror element may comprise a firstsubstrate 220 a, 220 b secured in a spaced-apart relationship with asecond substrate 225 via a primary seal 230 to form a chamber therebetween. At least a portion of the primary seal is left void to form atleast one chamber fill port 235. An electro-optic medium is enclosed inthe chamber and the fill port(s) are sealingly closed via a plugmaterial 240. Preferably, the plug material is a UV curable epoxy oracrylic material. Also shown is a spectral filter material 245 a, 245 blocated near the periphery of the element. Electrical clips 250, 255 arepreferably secured to the element, respectively, via first adhesivematerial 251, 252. The element is secured to a carrier plate 260 viasecond adhesive material 265. Electrical connections from the outsiderearview mirror to other components of the controlled vehicle arepreferably made via a connecter 270. The carrier is attached to anassociated housing mount 276 via a positioner 280. Preferably, thehousing mount is engaged with a housing 275 a, 275 b and secured via atleast one fastener 276 a. Preferably, the housing mount comprises aswivel portion configured to engage a swivel mount 277 a, 277 b. Theswivel mount is preferably configured to engage a vehicle mount 278 viaat least one fastener 278 a. Additional details of these components,additional components, their interconnections and operation are providedherein.

With further reference to FIG. 2 a, the outside rearview mirror assembly210 a is oriented such that a view of the first substrate 220 a is shownwith the spectral filter material 245 a positioned between the viewerand the primary seal material (not shown). A blind spot indicator 285, akeyhole illuminator 290, a puddle light 292, a turn signal 294, a photosensor 296, any one thereof, a subcombination thereof or a combinationthereof may be incorporated within the rearview mirror assembly suchthat they are positioned behind the element with respect to the viewer.Preferably, the devices 285, 290, 292, 294, 296 are configured incombination with the mirror element to be at least partially covert asdiscussed in detail within various references incorporated by referenceherein. Additional details of these components, additional components,their interconnections and operation are provided herein.

Turning now to FIG. 3, there is shown an inside rearview mirror assembly310 as viewed looking at the first substrate 322 with a spectral filtermaterial 345 positioned between the viewer and a primary seal material(not shown). The mirror element is shown to be positioned within amovable housing 375 and combined with a stationary housing 377 on amounting structure 381. A first indicator 386, a second indicator 387,operator interfaces 391 and a first photo sensor 396 are positioned in achin portion of the movable housing. A first information display 388, asecond information display 389 and a second photo sensor 397 areincorporated within the assembly such that they are behind the elementwith respect to the viewer. As described with regard to the outsiderearview mirror assembly, it is preferable to have devices 388, 389, 397at least partially covert. For example, a “window” may be formed in theassociated mirror element third and, or, fourth surface coatings andconfigured to provide a layer of a platinum group metal (PGM) (i.e.iridium, osmium, palladium, platinum, rhodium, and ruthenium) only onthe third surface. Thereby, light rays impinging upon the associated“covert” photo sensor “glare” will first pass through the first surfacestack, if any, the first substrate, the second surface stack, theelectro-optic medium, the platinum group metal and, finally, the secondsubstrate. The platinum group metal functions to impart continuity inthe third surface conductive electrode thereby reducing electro-opticmedium coloring variations associated with the window.

Turning now to FIGS. 4 a-4 e and 5, a discussion of additional featuresof the present invention is provided. FIG. 4 a depicts a rearview mirrorelement 400 a viewed from the first substrate 402 a with a spectralfilter material 496 a positioned between the viewer and a primary sealmaterial 478 a. A first separation area 440 a is provided tosubstantially electrically insulate a first conductive portion 408 afrom a second conductive portion 430 a. A perimeter material 460 a isapplied to the edge of the element. FIG. 4 b depicts a rearview mirrorelement 400 b viewed from the second substrate 412 b with a primary sealmaterial 478 b positioned between the viewer and a spectral filtermaterial 496 b. A second separation area 486 b is provided tosubstantially electrically insulate a third conductive portion 418 bfrom a fourth conductive portion 487 b. A perimeter material 460 b isapplied to the edge of the element. FIG. 4 c depicts a rearview mirrorelement 400 c viewed from a section line FIG. 4 c-FIG. 4 c of either theelement of FIG. 4 a or 4 b. A first substrate 402 c is shown to besecured in a spaced apart relation via a primary seal material 478 cwith a second substrate 412 c. A spectral filter material 496 c ispositioned between a viewer and the primary seal material 478 c. Firstand second electrical clips 463 c, 484 c, respectively, are provided tofacilitate electrical connection to the element. A perimeter material460 c is applied to the edge of the element. It should be understoodthat the primary seal material may be applied by means commonly used inthe LCD industry such as by silk-screening or dispensing. U.S. Pat. No.4,094,058 to Yasutake et al., the disclosure of which is incorporated inits entirety herein by reference, describes applicable methods. Usingthese techniques, the primary seal material may be applied to anindividually cut-to-shape substrate or it can be applied as multipleprimary seal shapes on a large substrate. The large substrate withmultiple primary seals applied may then be laminated to another largesubstrate and the individual mirror shapes can be cut out of thelaminate after at least partially curing the primary seal material. Thismultiple processing technique is a commonly used method formanufacturing LCDs and is sometimes referred to as an array process.Electro-optic devices can be made using a similar process. All coatingssuch as the transparent conductors, reflectors, spectral filters and, inthe case of solid state electro-optic devices, the electro-optic layeror layers may be applied to a large substrate and patterned ifnecessary. The coatings can be patterned using a number of techniquessuch as by applying the coatings through a mask, by selectively applyinga patterned soluble layer under the coating and removing it and thecoating on top of it after coating application, laser ablation oretching. These patterns can contain registration marks or targets thatcan be used to accurately align or position the substrates throughoutthe manufacturing process. This is usually done optically, for instance,with a vision system using pattern recognition technology. Theregistration marks or targets may also be applied to the glass directlysuch as by sand blasting, or laser or diamond scribing if desired.Spacing media for controlling the spacing between the laminatedsubstrates may be placed into the primary seal material or applied to asubstrate prior to lamination. The spacing media or means may be appliedto areas of the laminate that will be cut away from the finishedsingulated mirror assemblies. The laminated arrays can be cut to shapebefore or after filling with electro-optic material and plugging thefill port if the devices are solution phase electro-optic mirrorelements.

FIG. 4 d depicts a plan view of a second substrate 412 d comprising astack of materials on a third, fourth or both third and fourth surfaces.In at least one embodiment, at least a portion 420 d 1 of a stack ofmaterials, or at least the substantially opaque layers of a stack ofmaterials, are removed, or masked, beneath the primary seal material. Atleast a portion 420 d 2 of at least a layer of the stack of materialsextends substantially to the outer edge of the substrate or extends toan area to facilitate electrical contact between the third surface stackand an element drive circuit (not shown). Related embodiments providefor inspection of the seal and, or, plug viewing and, or, plug curingthe rear of the element subsequent to element assembly. In at least oneembodiment, at least a portion of an outer edge 420 d 1 of a stack ofmaterials 420 d is located between an outer edge 478 d 1 and an inneredge 478 d 2 of a primary seal material 478 d. In at least oneembodiment, the portion 420 d 1 of a stack of materials, or at least thesubstantially opaque layers of a stack of materials, are removed, ormasked, beneath the primary seal material between approximately 2 mm andapproximately 8 mm wide, preferably approximately 5 mm wide. At least aportion 420 d 2 of at least a layer of the stack of materials extendssubstantially to the outer edge of the substrate or extends to an areato facilitate electrical contact between the third surface stack and anelement drive circuit (not shown) between approximately 0.5 mm andapproximately 5 mm wide, preferably approximately 1 mm. It should beunderstood that any of the first, second, third and fourth surfacelayers or stacks of materials may be as disclosed herein or within thereferences incorporated elsewhere herein by reference.

FIG. 4 e depicts a plan view of a second substrate 412 e comprising athird surface stack of materials. In at least one embodiment, at least aportion of an outer edge 420 e 1 of a third surface stack of materials420 e is located between an outer edge 478 e 1 and an inner edge 478 e 2of a primary seal material 478 e. In at least one related embodiment, aconductive tab portion 482 e extends from an edge of the secondsubstrate inboard of an outer edge 478 e 1 of a primary seal material478 e. In at least one related embodiment, a conductive tab portion 482e 1 overlaps with at least a portion of a third surface stack ofmaterials beneath a primary seal material 478 e. In at least oneembodiment, a substantially transparent conductive layer (not shownindividually), such as a conductive metal oxide, of a third surfacestack of materials extends beyond an outer edge 420 e 1 of a remainderof the third surface stack and is in electrical communication with aconductive tab portion as depicted in FIG. 7 k. It should be understoodthat the conductive tab may be deposited along any of the substrateperipheral areas as shown in FIGS. 7 d-7 n. In at least one embodiment,a conductive tab portion comprises chrome. It should be understood thatthe conductive tab portion improves conductivity over the conductiveelectrode; as long as a conductive electrode layer is provided withsufficient conductivity, the conductive tab portion is optional. In atleast one embodiment, the conductive electrode layer imparts the desiredcolor-specific characteristics of the corresponding reflected light raysin addition to providing the desired conductivity. Therefore, when theconductive electrode is omitted, color characteristics are controlledvia the underlayer material specifications. It should be understood thatany of the first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

FIG. 5 depicts rearview mirror element 500 which is an enlarged view ofthe element depicted in FIG. 4 c to provide greater detail. Element 500comprises a first substrate 502 having a first surface 504 and a secondsurface 506. A first conductive electrode portion 508 and a secondconductive electrode portion 530 applied to the second surface 506 aresubstantially electrically insulated from one another via a firstseparation area 540. As can be seen, in at least one embodiment theseparation area is located such that the spectral filter material 596and a corresponding adhesion promotion material 593 are alsosubstantially electrically insulated to define first and second spectralfilter material portions 524, 536, respectively, and first and secondadhesion promotion material portions 527, 539, respectively. A portionof the first separation area 540, 440 a, 440 b, 440 c is shown to beextending parallel within a portion of the primary seal material 578located near the center thereof. It should be understood that thisportion of the separation area 540 may lie such that a viewer would notreadily perceive a line within the spectral filter material; forexample, a portion of the separation area may be substantially alignedwith an inboard edge 597 of spectral filter material 596. It should beunderstood that when any portion of the separation area 540 is locatedinboard of the primary seal material, as is described in more detailelsewhere herein, a discontinuity in the electro-optic material coloringand, or, clearing may be observed. This operational characteristic maybe manipulated to derive a subjectively visually appealing element.

With further reference to FIG. 5, the element 500 is depicted tocomprise a second substrate 512 having a third surface 515 and a fourthsurface 514. It should be noted that the first substrate may be largerthan the second substrate to create an offset along at least a portionof the perimeter of the mirror. Third and fourth conductive electrodeportions 518, 587, respectively, are shown proximate the third surface515 substantially electrically insulated via second separation area 586.A portion of the second separation area 586, 486 a, 486 b, 486 c isshown to be extending parallel within a portion of the primary sealmaterial 578 located near the center thereof. It should be understoodthat this portion of the separation area 586 may lie such that a viewerwould not readily perceive a line within the spectral filter material;for example, a portion of the separation area may be substantiallyaligned with an inboard edge 597 of spectral filter material 596. Asfurther shown in FIG. 5, a reflective material 520 may be appliedbetween an optional overcoat material 522 and the third conductiveelectrode portion 518. It should be understood that any of the materialsas disclosed in commonly assigned U.S. Pat. Nos. 6,111,684, 6,166,848,6,356,376, 6,441,943, 6,700,692, 5,825,527, 6,111,683, 6,193,378,6,816,297, 7,064,882 and 7,324,261, the disclosure of each of which isincorporated herein by reference, may be employed to define a unitarysurface coating, such as a hydrophilic coating on a first surface, or acomposite stack of coatings, such as conductive electrode material,spectral filter material, adhesion promotion material, reflectivematerial, overcoat material applied to the first, second, third andfourth surfaces. It should be additionally understood that a hydrophobiccoating, such as a fluorinated alkyl saline or polymer, a siliconecontaining coating or a specially textured surface may be applied to thefirst surface. Either a hydrophilic or hydrophobic coating will alterthe contact angle of moisture impinging upon the first surface relativeto glass with no such coating and will enhance rear vision when moistureis present. It should be understood that both third surface and fourthsurface reflector embodiments are within the scope of the presentinvention. In at least one embodiment, the materials applied to thethird surface and, or, fourth surface are configured to provide apartially reflective/partially transmissive characteristic for at leasta portion of the corresponding surface stack. In at least oneembodiment, the materials applied to the third surface are integrated toprovide a combination reflector/conductive electrode. It should beunderstood that additional “third surface” materials may extend outboardof the primary seal, in which case, it should be understood that thecorresponding separation area extends through the additional materials.Having at least a portion of the primary seal visible from the fourthsurface, as depicted in FIG. 4 d for example, facilitates inspection andUV curing of plug material. In at least one embodiment, at least aportion of a stack of materials 420 d, or at least the substantiallyopaque layers of a stack of materials, are removed, or masked, beneaththe primary seal material to provide for inspection of at least 25percent of the primary seal width around at least a portion of theperimeter. It is more preferred to provide for inspection of 50 percentof the primary seal width around at least a portion of the perimeter. Itis most preferred to provide for inspection of at least 75 percent ofthe primary seal width around at least a portion of the perimeter.Various embodiments of the present invention will incorporate portionsof a particular surface having a coating or stack of coatings differentfrom other portions; for example, a “window” in front of a light source,information display, a photo sensor, or a combination thereof may beformed to selectively transmit a particular band of light raywavelengths or bands of light ray wavelengths as described in many ofthe references incorporated herein.

With further reference to FIGS. 4 a-4 b and 5, the first separation area540 cooperates with a portion of the primary seal material 575 to definethe second conductive electrode portion 530, the second spectral filtermaterial portion 536 and the second adhesion promotion material portion539 substantially electrically insulated from the first conductiveelectrode portion 508, the first spectral filter material portion 524and first adhesion promotion material portion 527. This configurationallows for placement of an electrically conductive material 548 suchthat the first electrical clip 563 is in electrical communication withthe third conductive electrode portion 518, the reflective material 520,the optional overcoat 522 and the electro-optic medium 510. It should beapparent, particularly in embodiments wherein the electricallyconductive material 548 is applied to the element prior to placement ofthe first electrical clip 569, that electrically conductive material mayat least partially separate the interfaces 557, 566, 572, 575.Preferably, the material, or composition of materials, forming the thirdconductive electrode portion 518, the first electrical clip 563 and theelectrically conductive material 548 are chosen to promote durableelectrical communication between the clip and the materials leading tothe electro-optic medium. The second separation area 586 cooperates witha portion of the primary seal material 575 to define the fourthconductive electrode portion 587 substantially electrically insulatedfrom the third conductive electrode portion 518, the reflective layer520, the optional overcoat material 522 and the electro-optic medium510. This configuration allows for placement of an electricallyconductive material 590 such that the second electrical clip 584 is inelectrical communication with the first adhesion promotion materialportion 527, the first spectral filter material portion 524, the firstconductive electrode portion 508 and the electro-optic medium 510. Itshould be apparent, particularly in embodiments wherein the electricallyconductive material 590 is applied to the element prior to placement ofthe first electrical clip 584, that electrically conductive material mayat least partially separate the interfaces 585, 588, 589. Preferably,the material, or composition of materials, forming the first conductiveelectrode portion 508, the first electrical clip 584, the adhesionpromotion material 593, the spectral filter material 596 and theelectrically conductive material 590 are chosen to promote durableelectrical communication between the clip and the materials leading tothe electro-optic medium.

Preferably, the perimeter material 560 is selected such that theresulting visible edge surface is visually appealing and such that goodadhesion is obtained at interfaces 533, 545, 554. It should beunderstood that at least a portion of the first substrate 502 in theareas proximate the first corner 503, the edge 505, the second corner507 and combinations thereof may be treated to smooth protrusions anddepressions noticeable to a viewer. It is within the scope of thepresent invention to treat at least a portion of a surface, a corner, anedge or a combination thereof to define “beveled,” “rounded,” orcombinations thereof. Commonly assigned U.S. Pat. Nos. 7,064,882 and7,324,261 describe various mechanisms for carrying out the edgetreatment. The corresponding treatment improves the visual appearanceand durability of the element.

Turning to FIG. 6 and Tables 1-4a, the color rendered as a result ofhaving an indium-tin-oxide conductive electrode between the secondsurface of the first substrate and a spectral filter material or ring isdescribed. In the example mirror element description contained herein,the reflectivity associated with the spectral filter material withrespect to that of the third surface reflector results, in at least oneembodiment, in a more blue hue for the spectral filter material when theelectro-optic medium is in a “clear” sate. As depicted in the tablescontained herein, the b* of the reflector is higher than the b* of thespectral filter material. When there is mismatch between the hue of themain reflector and spectral filter material, it is often desirable tohave a spectral filter material with a lower b* value than the mainreflective area. Many outside mirrors are designed to have a bluish huein the main reflective area. As described in at least one embodimentherein, use of aluminum in combination with, or in lieu of, chrome forthe spectral filter material provides additional color renderingoptions. Other options, or embodiments, are depicted which provide abetter match between the ring and the mirror viewing area. In theseother cases the spectral filter or ring has virtually identicalreflectance and color allowing a seamless match between the viewing areaand the ring.

Table 1 summarizes various color characteristics, namely, Y specularincluded (A10); a*; b*; C* and Y specular excluded, for seven uniquelyconfigured spectral filter materials, second surface conductiveelectrode and related materials.

Tables 1a through 1d contain variations for the spectral filtermaterials. The reflectance is in CIE-D65. Individual layer thicknessesare in nanometers. Table 1a shows the effect of chrome thickness on thestack Glass/ITO/Cr/Ru/Rh. The reflectance of the stack increases as thethickness of the chrome is thinned. In this example the refractive indexof the chrome is n=3.4559 and k=3.9808, where n represents the realportion and k represents the imaginary portion of a complex number. Therefractive index of the chrome in part defines the reflectivity of thestack and will be discussed in more detail later. Also, as the chrome isthinned, the reflected a* values increase leading to a better match forthe ring material.

In at least one embodiment, the reflectivity of the spectral filter isincreased by putting rhodium next to the first chrome layer instead ofruthenium. Table 1b shows the effect of chrome thickness on thereflectance and color of the ring as the chrome thickness is changed.Again, like the previous example, the reflectance increases as thechrome layer is thinned. This example is preferred when the reflectanceof the center of the mirror reflectance is relatively high.

Typical production mirror properties are shown below:

Full Mirror Reference Color Reflectance a* b* Typical Outside Mirror56.3 −2.2 2.4 Typical Inside Mirror 85.0 −3.0 5.0

TABLE 1a alternate stacks - chrome thickness with ruthenium CIE-D65 Run# ITO Cr Ru Rh Cr Ru Rh R a* b* 1 118 60 20 3.5 45.5 −6.1 −3.1 2 118 2020 3.5 47.5 −4.9 −2.8 3 118 10 20 3.5 50.24 −4.3 −2.3 4 118 5 20 3.551.16 −4.3 −2.1 5 118 2.5 20 3.5 51.17 −4.3 −1.9

TABLE 1b alternate stacks - chrome thickness with rhodium/rutheniumCIE-D65 Run # ITO Cr Ru Rh Cr Ru Rh R a* b* 17 118 0 5 30 59.82 −3.3−0.14 18 118 2.5 5 30 57.36 −3.2 −0.6 19 118 5 5 30 54.9 −3.3 −1.1 20118 7.5 5 30 52.64 −3.6 −1.6 21 118 10 5 30 50.66 −3.9 −2.2 22 118 12.55 30 49.02 −4.3 −2.6

Table 1c depicts the effect of ruthenium thickness when a thin rhodiumlayer is used next to a thin chrome layer. A particular benefit isattained when the ruthenium is approximately 20 nm. The minimumrequirement of ruthenium will vary with rhodium thickness, the thinchrome thickness and the target reflectivity value.

TABLE 1c alternate stacks - varying ruthenium behind rhodium Run # ITOCr Ru Rh Cr Ru Rh CIE-D65 R a* b* 11 118 5 2.5 0 19.63 −8.5 −3.4 12 1185 2.5 10 44.46 −4.7 −2.8 13 118 5 2.5 20 52.9 −3.7 −1.6 14 118 5 2.5 3053.97 −3.6 −1.3 15 118 5 2.5 40 53.4 −3.9 −1.6

Table 1d depicts the how the reflectance will change with rhodiumthickness at a fixed chrome and ruthenium thickness. The intensity ofthe reflectance increases with increasing rhodium thickness and thereflected a* increases. The increase in the reflected a* may beexploited to help improve the color match between the center of glassand the ring. The change in reflectance with changing rhodium thicknesswill differ depending on the thickness of the chrome layer between therhodium and the ITO. The thicker the chrome layer, the more the rhodiumreflectance will be dampened. Also in Table 1d are alternate metalsbetween a thin and thick chrome layer. Palladium, iridium, cadmium andplatinum are shown. The reflectance versus metal thickness is shownalong with the effect of changing the thin chrome base layer thickness.

TABLE 1d alternate stacks - varying rhodium thickness Run # ITO Cr Ru RhCr Ru Rh CIE-D65 R a* b* 118 5 0 30 52.59 −4 −1.6 14 118 5 2.5 30 53.97−3.6 −1.3 16 118 5 5 30 54.9 −3.3 −1.1 19 118 5 7.5 30 55.5 −3.1 −0.9Glass 1.2 mm 1.2 mm 1.2 mm 1.2 mm 1.2 mm 1.2 mm ITO 120 120 120 120 120120 IRIDIUM 3 6 9 12 15 18 CR 40 40 40 40 40 40 R (cap Y) 50.5 52.8 54.355.4 56.0 56.4 ITO 120 120 120 120 120 120 Chrome 1 2 4 6 8 10 IRIDIUM15 15 15 15 15 15 CR 40 40 40 40 40 40 R (cap Y) 55.3 54.5 53.3 52.251.4 50.8 ITO 120 120 120 120 120 120 Palladium 3 6 9 12 15 18 CR 40 4040 40 40 40 R (cap Y) 50.9 53.6 55.6 57.0 58.0 58.7 ITO 120 120 120 120120 120 Chrome 1 2 4 6 8 10 Palladium 15 15 15 15 15 15 CR 40 40 40 4040 40 R (cap Y) 56.5 55.2 53.0 51.5 50.4 49.6 ITO 120 120 120 120 120120 Platinum 3 6 9 12 15 18 CR 40 40 40 40 40 40 R (cap Y) 49.7 51.352.3 52.9 53.1 53.2 ITO 120 120 120 120 120 120 Chrome 1 2 4 6 8 10Platinum 15 15 15 15 15 15 CR 40 40 40 40 40 40 R (cap Y) 52.3 51.6 50.549.7 49.2 48.9 ITO 120 120 120 120 120 120 Cadmium 3 6 9 12 15 18 CR 4040 40 40 40 40 R (cap Y) 52.3 56.5 59.9 62.5 64.6 66.1 ITO 120 120 120120 120 120 Chrome 1 2 4 6 8 10 Cadmium 15 15 15 15 15 15 CR 40 40 40 4040 40 R (cap Y) 62.2 60.1 56.6 54.0 52.0 50.7

Different metals or mixtures of metals may be used next to the thinchrome layer. The thin chrome layer may be considered optional.Generally, the thin chrome layer is used when an adhesion promoter layeris desired. Alternate adhesion promoting metals or materials may fulfilla comparable function. The different metals are selected to alter thereflectance, either higher or lower, depending on the match desired withrespect to the center of the viewing area. The metal can have anotherbenefit, that of altering the color or hue of the ring area. Thepresence of the ITO or other dielectric layer under the metals tends tomove the color to a more negative b* direction. The use of a “red” highreflectance metal such as copper may enhance reflectivity whilesimultaneously facilitating a color match to the viewing area. Table 1eshows the effect of a thin copper layer placed between two chromelayers. The reflectance is substantially increased while simultaneouslymaking the ring color more neutral. A copper gold alloy has similarproperties.

TABLE 1e Color and reflectance effects of copper addition to stack ITO114 114 Chrome 1 1 Copper 0 15 Chrome 40 40 R 47.3 56.2 a* −5.2 −0.7 b*−3.5 2.3

Suitable metals, which will result in increased reflectance, includecadmium, cobalt, copper, palladium, silver, gold, aluminum and iridiumor other high reflectance metals, their alloys and/or mixtures ofmetals.

TABLE 1 D65-2 Macbeth Color Eye 7000 Reflectance A10 D65-2 (specularincluded) Y Trial Y a* b* C* specular excluded 1 856csito 11.665 2.088−5.491 5.874 0.01 2 cswchr 38.312 −3.477 4.183 5.439 0.133 3 cswchral61.366 −3.108 6.965 7.627 0.186 4 halfchral 61.679 −4.484 12.279 13.0720.376 5 halfchr 41 −5.929 12.809 14.114 0.073 6 Tec15Chr 23.76 0.9848.603 8.659 1.322 7 Tec 15 11.284 −3.363 0.442 3.392 0.162 1 - Glass/856Ang. Al203/Half wave (Optical thickness) ITO 2 - 1 plus opaque chromelayer 3 - 1 plus approx 30 Ang. Chrome/250 Ang. Aluminum 4 - Glass/Halfwave ITO/30 Ang. Chrome/250 Ang. Aluminum 5 - Glass/Half wave ITO/OpaqueChrome layer 6 - Glass/Tec15/Opaque chrome 7 - Tec 15

Table 2 summarizes various color characteristics, namely, a*; b*; C* andY specular included (A10) for the combinations of variousindium-tin-oxide second surface conductive electrodes positioned betweena first substrate and a substantially opaque chrome spectral filtermaterial. The data contained in this table depicts the ability tocontrol the resulting b* value by varying the ITO thickness fromapproximately 65 percent to approximately 100 percent of a half-wavethickness. Specific thicknesses anticipated to obtain a given color mayvary somewhat based on deposition parameters that affect the opticalconstants. The color of a particular stack may vary, to some degree,based on choice of process parameters, as well as process fluctuationsthat result in small but sometimes significant shifts in the opticalconstants of the materials used. For example, the half-wave opticalthickness of ITO will correspond to a lesser physical thickness if thephysical density of the coating is increased and an increase inabsorption in the ITO coating would decrease the reflectivity of asecond surface ITO plus chrome stack. This does not negate the fact thatover the range of optical constants usually associated with ITO, a halfwave optical thickness of ITO (relative to 550 nm) when coated with, forexample, chrome, will tend to produce a reflection having a yellowishhue. Table 2a shows the same effect over a narrower range of ITOthicknesses and with a modified metal stack. As the ITO is increased inthickness, the reflectance increases providing a better intensity match.The a* value decreases and the b* value increases. The net effect isthat the color match will be improved with the appropriate ITOthickness. Or, if a color mismatch is chosen, the color of the spectralfilter material can be made to have a lower b* value than the mainreflective area.

TABLE 2 TCO plus Chrome Specular Included Trial a* b* C* A10Y 85CHR−6.801 2.486 7.241 44.829 80CHR −6.717 −0.829 6.768 44.375 75CHR −6.024−4.031 7.248 43.759 70CHR −5.613 −5.426 7.807 42.917 65CHR −5.227 −6.6398.45 42.64 100CHR  −7.06 12.85 14.662 45.255

TABLE 2a Effect of ITO with modified metal stack Run # ITO Cr Ru Rh CrRu Rh CIE-D65 R a* b* 108 5 2.5 30 52.3 −2.5 −4.5 113 5 2.5 30 53.2 −3.1−3.0 118 5 2.5 30 54.0 −3.6 −1.3 123 5 2.5 30 54.5 −4.1 0.6 128 5 2.5 3054.9 −4.5 2.6 133 5 2.5 30 55.1 −4.7 4.7

Table 3 summarizes various color characteristics, namely, a*; b*; C* andY specular included (A10) for various indium-tin-oxide second surfaceconductive electrodes. The data contained in this table depicts theresulting values produced by varying the ITO thickness fromapproximately 65 percent to approximately 100 percent of a half-wavethickness.

TABLE 3 TCO Specular Included Thickness Trial a* b* C* A10Y (Å) 65CLR−0.988 15.535 15.567 15.678 1095 100CLR  13.588 −17.765 22.366 8.9671480 85CLR 8.376 2.896 8.863 11.352 1306 80CLR 4.481 11.34 12.193 12.8921253 75CLR 1.565 15.019 15.101 14.275 1194 70CLR −0.276 15.654 15.65615.259 1135

Materials used for transparent second surface conductive electrodes aretypically materials with an approximately 1.9 index of refraction, orgreater. It is known to minimize color impact of these conductiveelectrode materials by using half wave thickness multiples, using thethinnest layer possible for the application or by the use of one ofseveral “non-iridescent glass structures.” Non-iridescent structureswill typically use either a high and low index layer under the highindex conductive coating (see, for example, U.S. Pat. No. 4,377,613 andU.S. Pat. No. 4,419,386 by Roy Gordon), or an intermediate index layer(see U.S. Pat. No. 4,308,316 by Roy Gordon) or graded index layer (seeU.S. Pat. No. 4,440,822 by Roy Gordon) to minimize color impact. Theintensity of the ring with a color suppression layer is lower than thecenter of the part. The color suppression layer helps the color of thering but the ring would still be visible because of the intensitycontrast. The color suppressed ITO would therefore benefit from the useof a different sequence of metal layers on top of the ITO. Table 3ashows the color for a range of different metal options. The top chromelayer is optional and it does not contribute to the color or reflectancematch of the ring. The top chrome layer is added to minimize thetransmittance of the layer stack and to minimize the amount of UV lightthat would reach the seal, thus extending the lifetime of the product. Achrome/rhodium/ruthenium stack is shown but it is understood that othermetals, alloys, and high reflectors described elsewhere in this documentcan be used.

The results of varying the thickness of the ITO with and without a colorsuppression layer are shown in Table 3a2. The colors shown in the tablerepresent the changes which occur with an ITO thickness between 100 and300 nm. Therefore, the use of a color suppression layer allows a broaderthickness range for the ITO layer without causing the strong colorvariations experienced without the color suppression layer.

A partially transmissive layer such as thin chrome adjacent to the glassmay be used to provide adhesion benefits compared to metals that mightbe used for better reflectivity compared to chrome such as a platinumgroup metal (PGM) (i.e. iridium, osmium, palladium, platinum, rhodium,and ruthenium), silver, aluminum and various alloys of such metals witheach other, such as silver-gold, white gold, or other metals. When theseother metals or alloys are placed behind the partially transmissiveadhesion promoting layer, some of the improved reflectance of the secondmaterial will be realized. It may also be beneficial to overcoat thespectral filter material with a material that improves the durability ofthe spectral filter material whether it is in contact with a transparentconductor overcoat or if it is in direct contact with the electro-opticmedium. It should be understood that the reflector may be a dichroicstack. The spectral filter material may comprise a single material suchas chrome or may comprise a stack of materials such as: 1) chrome,rhodium, ITO; 2) moly; 3) chrome, rhodium, TCO; 4) chrome, platinumgroup metal, ITO; 5) ITO, silver, ITO; 6) ITO, silver alloy, ITO; 7)Z_(N)O, silver/silver alloy, Z_(N)O; 8) transparent conductor, metalreflector, transparent conductor; silicon, ITO; 9) silicon, Z_(N)O; 10)chrome, ruthenium, ITO and 11) chrome/rhodium/rutheniun/ITO or othermetals, metal alloys or combinations described elsewhere in thisdocument can be used.

TABLE 3a Effect of metal layers with color suppressed ITO - Reflectancein CIE-D65 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Example 7 Example 8 Example 9 Example 10 Example 11 Color 80 80 80 80 8080 80 80 80 80 80 Suppression Layer ITO ½ 148.7 148.7 148.7 148.7 148.7148.7 148.7 148.7 148.7 148.7 148.7 Wave Chrome 0 3 5 5 5 5 5 4 3 2 60Layer Rhodium 0 0 0 3 6 9 12 12 12 12 0 Ruthenium 30 30 30 30 30 30 3030 30 30 30 Chrome 25 25 25 25 25 25 25 25 25 25 0 Layer Reflectance48.8 49.2 49.3 51.1 52.2 52.9 53.2 54.3 55.5 56.8 45.7 Cap Y a* −2.2−1.6 −1.4 −0.9 −0.5 −0.2 0.0 0.0 −0.1 −0.2 −1.8 b* 2.1 0.5 −0.3 −0.3−0.3 −0.2 −0.2 0.4 1.0 1.7 −3.3

TABLE 3a2 Effect of color suppressed ITO thickness on color - 200 nm ITO+/− 100 nm Stack Case 1 Case 2 Case 3 Case 4 Case 5 Case 6 Case 7 Case 81.670 80 80 80 80 80 80 80 80 ITO 100 130 150 180 210 240 270 300 Chrome2 2 2 2 2 2 2 2 Rhodium 5 5 5 5 5 5 5 5 Ruthenium 30 30 30 30 30 30 3030 a* 1.15 0.54 −0.76 −1.5 0 0.54 −0.84 −1.1 b* 0.9 0.14 1.7 3.22 0.92−0.16 2.17 3.1 1.670 0 0 0 0 0 0 0 0 ITO 100 130 150 180 210 240 270 300Chrome 2 2 2 2 2 2 2 2 Rhodium 5 5 5 5 5 5 5 5 Ruthenium 30 30 30 30 3030 30 30 a* −1 −3.9 −3.4 5.5 8 −4 −10.1 −0.9 b* −5.4 3.19 9.9 3.8 −8.6−4.3 7.6 5.5

There may also be advantages to applying the transparent conductiveoxide(s) on the second surface of the mirror in more than one step. Forexample, a zinc oxide layer may be deposited initially to form a layerto which silver or its alloys bond well. This is preferably chosen at athickness that produced a desirable color and reflectivity when combinedwith silver, silver alloy or other metals and their alloys. Then themetal layer(s) are applied around the perimeter of the part followed byadditional transparent conductive oxide(s) over at least theelectrochromic area. The additional applications of oxides improve theconductivity in the electrochromic area and may be chosen at a thicknesswhich yields a desirable range of hue when going from bright state todark state, in the electrochromic area, but particularly in the fullydarkened state. If the conductive oxide adjacent to the electrochromicmedium has sufficient conductivity, not all of the metal oxides in thestack would necessarily need to be conductive.

For example, using an optical model, opaque silver deposited over 100 nmof ITO, the color of a reflective ring would be about, using D65illuminant, 2 degree observer a*=−1, b*=−2 and Y value of 89. Forpurposes of this discussion, the silver is masked such that it is onlyapplied in a ring around the electrochromic area. The color of theelectrochromic area with only the 100 nm ITO on glass using a materialof index 1.43 as the electrochromic medium and no reflection from a3^(rd) or 4^(th) surface models as a*=−3, b*=8 with a Y value of 8. Tomake the electrochromic area less yellow and more conductive, 40 nm ofITO coating may be added in the electrochromic area. This brings thecoating in the electrochromic area to about half wave optical thickness,which is approximately the second surface coating thickness that mostelectrochromic elements have. The model for the electrochromic area thenyields a color of a*=11, b*=−14, and Y value of 5. Either, or both, ofthese applications of transparent conductive oxides may be of anothermaterial such as aluminum doped zinc oxide. There might also beadditional layer(s) such as nickel chromium or nickel chromium suboxide,niobium or niobium suboxide, titanium or titanium suboxide, as well asother means known in the art that would protect or preserve a metallayer such as silver during subsequent steps of the coating and assemblyprocess such as thermal processing steps.

Note that by using such a stack, the reflective ring will more closelymatch the brightness of electrochromic areas in the undarkened statethat are more highly reflective such as devices that have 3^(rd) surfacecoatings incorporating silver or silver alloys.

In particular, aluminum in direct contact with the electro-optic mediumtends to degrade upon being subjected to multiple coloring/clearingcycles. An overcoat of chrome has been demonstrated to improve thatdurability. When an ITO overcoat is used, a material such as silicon mayimprove the strength of the bond between the ITO and the substancescloser to the glass. Other materials, such as a platinum group metal(PGM) (i.e. iridium, osmium, palladium, platinum, rhodium, andruthenium), may be overcoated to improve adhesion reflection conductionelectrode stability, any one thereof, subcombinations thereof orcombinations thereof, characteristics.

As revealed in the above figures and tables, the thickness of ITO may bechosen to produce a desired reflection color. If the ITO coating isabout 25 percent thinner, that is about 120 Å. Instead of 140 Å, then amore bluish hue results (i.e. lower b*). This, however, will also resultin decreased conductivity of the ITO coating. The reflectivity of thecoating will also be slightly to somewhat higher than for coatings ofthe traditional half-wave optical thickness where the reference is to aminimum reflectivity near 550 nm.

The compromise between optimal color and sheet resistance of the ITO maybe mitigated by the use of partial deletion of the ITO layer. Forinstance, the ITO may be applied to any thickness needed to giveadequate color in the center of the viewing area and the required sheetresistance. Then, the ring portion of the ITO coating may be ion etchedor removed in any other viable method so that the final thickness of theITO in the ring is at a point where we have the desired aesthetics. Theetching or removal process for the ITO may be conducted in the sameprocess as the deposition of the subsequent metal layers or it may bedone in a separate step.

It is known in the art that a chrome layer may be applied beneath theITO layer to provide a marginal match between the viewing area and thering. The degree of match between the ring in this case and the viewingarea is a function of the reflectance in the viewing area and propertiesof the chrome. What has not been taught in the art is how the propertiesof the chrome layer affect the match of the ring to the viewing area.For instance, in some cases, the reflectance of the viewing area may bespecified by law to be greater than 55 percent. The reflectance of thechrome ring is a function of the thickness of the chrome and, moreimportantly, the refractive index of the chrome. For a given refractiveindex dispersion formula, the reflectance can be dropped from itsmaximum value by reducing the thickness of the chrome layer. This canhave a detrimental effect because the transmittance of the chrome layerwill increase thus allowing more UV light to penetrate to the EC unitseal. The UV light can damage the seal leading to a shorter lifetime ofthe product.

The reflectance of the ring may be enhanced by tuning the opticalproperties of the chrome layer. Table 3b shows the dependence of thereflectance of chrome under ITO on the optical properties of the chromelayer. Two sets of optical constants were obtained from the openliterature and were mixed in different proportions to assess the effectof the optical constants on the reflectivity. The optical constants varywith wavelength and the values in Table 3b are values at 550 nm forreference. The thickness of the chrome layer is 80 nm and the ITO is148.7 nm. In at least one embodiment, the glass thickness is 1.2 mm andthe reflectance quoted is for viewing through the glass to the coatingstack.

The reflectance, in this example, varies from a low of 48.6 to a high of54.2 percent. This clearly demonstrates that some chrome layers may notnecessarily attain the reflectance needed for a match to the reflectancein the viewing when relatively high reflectance is present in theviewing area. In addition, there is a finite maximum reflectanceattainable by a single layer of chrome under the ITO. The preferredchrome layers are defined by the refractive indices of the chrome layer.

TABLE 3b Performance of the chrome layer under ITO versus chrome forvarious chrome optical constants Chrome Layer 80 80 80 80 80 (nm) Chromen 3.456 3.366 3.279 3.196 3.116 @550 nm Chrome k 3.981 4.089 4.199 4.3104.423 @550 nm ITO-B18 148.7 148.7 148.7 148.7 148.7 (nm) Reflectance48.6 49.9 51.3 52.8 54.2 (percent)

In order to define the appropriate optical constants for the chromelayer, a series of calculations were performed. A simplified analysiswas conducted where the refractive index of the chrome is held constantover the visible region. The analysis shows the relationship between thereal and imaginary refractive indices of the chrome and the resultantreflectance. In actual practice, this may deviate from theoreticalanalysis by up to +/−20 percent to account for the effects of thedispersion in the chrome optical constants. Table 3c shows thereflectance for various combinations of n and k and the ratio of n/k.

TABLE 3c Reflectance for chrome under ITO as a function of the opticalconstants of the chrome @550 nm Example n k ratio Reflectance 1 3.003.90 0.77 49.8 2 3.00 4.10 0.73 51.7 3 3.00 4.20 0.72 52.7 4 3.00 4.200.71 52.7 5 3.00 4.30 0.70 53.7 6 3.00 4.50 0.67 55.5 7 2.70 4.20 0.6454.2 8 2.90 4.20 0.69 53.1 9 3.00 4.20 0.71 52.7 10 3.00 4.20 0.72 52.711 3.10 4.20 0.74 52.2 12 3.50 4.20 0.83 50.9 13 3.70 4.20 0.88 50.4 143.90 4.20 0.93 50.1 15 4.10 4.20 0.98 49.8 16 3.30 4.20 0.79 51.5 173.30 3.90 0.85 48.7 18 2.70 3.50 0.77 46.8 19 2.70 3.70 0.73 49.0 202.70 3.90 0.69 51.2 21 2.70 4.10 0.66 53.2 22 2.70 4.30 0.63 55.2 232.70 4.50 0.60 57.2 24 3.30 4.04 0.82 50.0

An analysis of this data set was conducted to determine an equationrelating n and k to reflectance. Again, the reflectance is calculatedwhen viewed through the glass.

Reflectance=9.21972−8.39545*n+20.3495*k+1.76122*n̂2−0.711437*k̂2−1.59563*n*k

The results can also be shown graphically. Using the equation and/orgraph we can determine the needed n and k values necessary to attain adesired degree of reflectivity for a chrome layer.

Aesthetically, it is desirable for the ring to match the viewing area asclosely as possible. The eye is then not drawn to the ring and canbetter focus on the object in the viewing area. It is somewhatsubjective what difference in appearance between the ring and viewingarea is objectionable. The intensity between the ring and viewing areais preferably within 10 percent, more preferably within 6 percent andmost preferably within 3 percent. Similarly, the color of the ring maybe objectionable. The color difference between the ring and viewing areashould be less than 30, preferably less than 15 and most preferably lessthan 10 C* units.

There may be situations where, due to processing limitation orrestrictions, it is not possible to attain the desired chrome opticalconstants, but a match is still desired between the ring and the viewingarea. In other situations it may be desirable to attain a reflectancefor the ring which is higher than what is possible with chrome alone. Inthese circumstances an approach similar to what was discussed above forthe case of the metals on top of the chrome may be applied. To attainhigher reflectance, a relatively thin layer of chrome is applied to theglass followed by a higher reflecting metal layer such as rhodium,ruthenium, iridium, cadmium, palladium, platinum or other appropriatemetal or alloy which has an inherent higher reflectance than chrome.

Table 3d shows the effect of chrome thickness on the reflectance for afixed n and k value for the chrome layer. The optical constants for thechrome were selected to produce a reflectance less than 50 percent withthe goal to match a viewing area reflectance of 56 percent. Thereflectance varies with the thickness of the first chrome layer with,essentially, a perfect match when the chrome layer thickness is reducedto 2.5 nm.

TABLE 3d Chrome thickness effect on reflectance Modified stack tocompensate for change in chrome properties Chrome optical constants n3.456 k 3.981 Chrome Layer 40 30 20 10 5 2.5 (nm) Ruthenium 35 35 35 3535 35 (nm) Chrome Layer 0 10 20 30 35 37.5 (nm) ITO-B18 148.7 148.7148.7 148.7 148.7 148.7 (nm) Reflectance 48.4 48.5 49.7 52.8 54.9 55.8(percent)

The optical constants of the chrome layer also have an effect on thereflectance of this stack. The reflectance may be attenuatedsignificantly with the optical constants of the chrome but with the useof a thin chrome layer backed by a higher reflectance metal layer,ruthenium in this case, the reflectance may be significantly increasedcompared to the case where the high reflectance metal is not present.Table 3e shows the effect of optical constants of the chrome on thereflectance.

TABLE 3e Effect of Chrome optical constants on reflectance Effect ofChrome base layer optical constants on reflectance Chrome Layer 10 10 1010 Ruthenium 35 35 35 35 Chrome Layer 30 30 30 30 ITO-B18 148.7 148.7148.7 148.7 Reflectance 53.5 54.9 55.9 56.9 Chrome n 3.366 3.279 3.1963.116 Chrome k 4.089 4.199 4.310 4.423

Another option for enhancing the reflectance of the ring and improvingthe aesthetic match to the viewing area consists of putting a low indexmaterial between the ITO and the metal layers. The low index layer maybe silica, alumina, MgO, polymer or other suitable low index material.At least options for the low index material exist. A first is to controlthe thickness of the silica layer to provide an interferential increasein reflectance. Table 3f compares the color of the ring with and withoutthe addition of the low index layer. In this case, the low index layeris silica but, as mentioned above, any appropriate low index material issuitable for this application. The thickness of the ITO and low indexlayers may be adjusted to alter the color while simultaneouslyincreasing the reflectance. The reflectance may be further increased bycombining this technique with the different metal stacks describedelsewhere in this document.

TABLE 3f Effect of addition of low index layer between the ITO and metallayers Case 1 Case 2 ITO 125 125 SIO2 0 55 Chrome 60 60 R 46.6 54.2 a*−6.6 −0.5 b* 0.9 3.0

Another option is to insert a relatively thick low index materialbetween the ITO and the metal reflectors of the ring. In this case, itis desirable that the low index layer be thick enough to act as a bulklayer. The necessary thickness is dependent, at least in part, on thematerial properties of the bulk layer, particularly if theinhomogeneities help to eliminate the phase information of the light.The thickness of the layer may be as thin as ¼ micron or thicker to getthe desired effect.

Other options to provide a match between the ring and the viewing areainclude the use of a High/Low/High dielectric stack. A series ofdielectric layers with alternating refractive indices may be used toprovide a high reflectance coating. For example, TiO2/SiO2/TiO2alternating layers may be used. Table 3g shows a stack consisting ofTiO2, SiO2 and ITO (thicknesses in nm) which provides a reflectance ofthe ring of 60.5 percent with a neutral color. The color and reflectancemay be modified by adjusting the thickness of the layers. A secondoption, with ITO as the base layer, is also shown in Table 3g. The stackmay be adjusted with both configurations to give both the desired colorand reflectance values. The thickness of the ITO may be adjusted toprovide for a more conductive layer. The thickness and indices of theother layers may be adjusted to compensate for the changes in the ITOthickness. This increases the utility of this design option.

TABLE 3g High/Low/High stack for ring match Glass 1.6 mm Glass 1.6 mmTIO2 55.3 ITO 148.7 SIO2 94.5 SIO2 90 TIO2 55.3 TIO2 50 SIO2 94.5 SIO290 ITO 148.7 TIO2 55 Reflectance 60.5 Reflectance 60.7 a* −5.3 a* −4.9b* 5.64 b* −1.9

Another option for the ring is the use of an IMI, orinsulator/metal/insulator, stack for the electrode. Some particular IMIstacks and ring materials are noted below but other versions are alsoviable. In the context of this invention, it may be assumed that an IMIstack may be substituted for ITO or another TCO. A metal or dielectricstack is then put between the IMI stack and the substrate or the sealmaterial. Both scenarios will work well. When the reflecting stack isput between the IMI and the glass, a more flexible situation for the IMIstack is achieved, particularly if the metal reflectors are essentiallyopaque. The IMI is shielded by the metal reflectors and may be adjustedas needed for the center viewing area. When the IMI is in between theglass and the reflecting stack, it is desirable to ensure that therequirements in the viewing area and ring are compatible. This may beaccomplished but it does impose limitations on the IMI stack which arenot present when the reflectors are between the IMI and the glass.

In the IMI stack the insulator may be a dielectric layer such as TiO2,SiO2, ZnO, SnO2, Niobium oxide, silicon metal, ZrOx, SiN or othersuitable material. Mixed oxides, oxynitrides or other composites may beused. The metal is preferably Ag or an alloy of Ag. The Ag may bealloyed or doped with Au, Pd, Pt, Si, Ti, Cu or other materials selectedto provide the proper electrochemical, chemical or physical properties.Protective layers may be placed between the metal layer and thedielectrics to improve adhesion, chemical stability of the metal orthermal stability of the IMI coating during heat treatment. Multipledifferent dielectrics may be used to attenuate color and reflectance inthe viewing area and in the ring.

TABLE 3h IMI stacks and ring reflectance. Thicknesses are in nm unlessnoted Glass 1.6 mm Glass 1.6 mm Glass 1.6 mm Glass 1.6 mm Glass 1.6 mmGlass 1.6 mm Cr 45.0 Cr 30.0 Cr 20.0 Cr 0.0 Cr 0.0 Cr 40.0 ZnO 39.8 ZnO39.8 Ru 15.0 Ru 0.0 Ru 0.0 Ru 0.0 Ag 9.0 Ag 9.0 ZnO 39.8 ZnO 39.8 TiO223.5 TiO2 23.5 ITO 52.8 ITO 52.8 Ag 9.0 Ag 9.0 ZnO 10.5 ZnO 10.5 Cr 0.0Cr 0.0 ITO 52.8 ITO 52.8 Ag 9.0 Ag 9.0 R 54.2 R 53.2 Cr 0.0 Cr 10.0 ITO35.7 ITO 35.7 a* −4.9 a* −5.6 R 55.9 AL 40.0 Ru 0.0 Ru 0.0 b* 0.5 b* 1.3a* −4.3 R 57.5 Cr 25.0 Cr 0.0 b* 0.9 a* −1.5 R 54.3 R 55.1 b* 8.4 a*−3.4 a* −5.0 b* −0.2 b* 0.8

When the ITO thickness is increased from a half-wave to the point wherea bluish color is achieved for the ITO plus chrome stack, the color ismuch more susceptible to shifts due to thickness variations duringdeposition and/or due to viewing angle differences in actual use. ITOcoatings deposited intentionally thinner than half-wave opticalthickness, per the discussion above, also exhibited relatively lowlevels of haze when overcoated with chrome as depicted in Table 2.

The difference between coatings may be measured by using the specularexcluded option available on some reflectance spectrophotometers. It isimportant to check that such measurements are actually measuringscattered light and not primarily small amounts of the specularcomponent. In general, shorter wavelengths of light scatter morereadily. That fact is a good indicator when used to determine whether agiven reading is actually the expected scattered light intensity beingmeasured. A MacBeth Color Eye 7000 is one spectrophotometer that givesgood haze measurement results in this regard.

As used herein, the terms “haziness” and “haze” should be understood torefer to the property of scattering, or non-specular reflection, in thinfilms. Haziness may be caused by a number of factors, including, lessthan fully oxidized layers, crystal sizes within a layer, surfaceroughness, layer interface properties, quality of cleaning of thesubstrate, subcombinations thereof and combinations thereof.

These properties may vary due to processing conditions and/or thematerials. This is especially true with processing conditions, in thatthe level of haze may vary substantially even within a single process“batch” or “load” of coatings. Nonetheless, for an ITO layer overcoatedwith chrome and viewed through the glass, whether with or without colorsuppression or anti-iridescent underlayers, it has been shown to bepossible to produce coatings much less hazy than those similarlyobtained with Tec 15 glass from Libbey-Owens-Ford.

Aluminum oxide may be used as an underlayer to assist in controlling thehue of the spectral filter material stack, as well as mixtures of oxidesyielding an appropriate refractive index. It may be particularlyadvantageous to use a mixture of ITO and SiO₂ and/or SiO as anunderlayer for ITO to control the resulting hue of the spectral filtermaterial stack. The use of ceramic targets for ITO is often consideredcapable of tighter process control for properties such as filmthickness. A sputter target comprising ITO and Si and/or Si in a mixtureof oxidation states may be employed. Such an underlayer potentiallyenables one to use an in-line coating system that does not havesubstantial gas flow isolation from either pumping or intervening doorsbetween the cathodes used for depositing the underlayer and the ITOlayer. A mixture of ITO and SiO₂ to at least some percentage of SiO₂will retain sufficient conductivity such that RF sputtering is notnecessary. Radio Frequency (RF) sputtering, as compared to MediumFrequency (MF) sputtering or direct current (DC) sputtering, oftenrequires electrical isolation and impedance matching that is not trivialto include in a thin film coating system.

Since there are regulatory requirements for 35 percent (40 percent inmany European countries) reflectivity for vehicular rearview mirrors(clear state for electro-optic mirror elements), in order for theperimeter area to be included in the field of view calculations, itneeds to have such a level of reflectance. In the data provided hereinwith respect to chrome over Tec 15 glass, this minimum is not met.

Use of a measurably hazy CVD deposited flourine doped tin oxide that ispart of an anti-iridescent structure for use in electro-optic devices isknown. Various thicknesses of ITO are known for providing a conductiveelectrode. It has not previously been known that the b* of anindium-tin-oxide conductive electrode and chrome spectral filtermaterial stack may be predictably controlled by varying the thickness ofthe ITO. Pyrolitically deposited fluorine doped tin oxide with ananti-iridescent structure (Tec 15 from L.O.F) is substantially more hazywhen overcoated with chrome compared with ITO deposited over a layer ofaluminum oxide as shown in Table 1.

In embodiments where the spectral filter material is located proximatethe first surface, it can be advantageous to minimize the distancebetween the first surface and the third or fourth surface reflector. Thegreater the distance between the reflector and the first surface, thegreater the discontinuity will be in the image reflected by the elementwhen transitioning from the main reflector to the spectral filtermaterial. This will be accentuated as the viewing angle increases.

In embodiments where a spectral filter material is located proximate thesecond surface of the element and an additional coating, such as ahydrophilic coating, is on the first surface, the optical properties ofboth coatings will affect the appearance of the perimeter of the deviceand may require adjustments to the layers for optimal appearance of theperimeter. In the case of an electro-optic element with a hydrophiliccoating as described in commonly assigned U.S. Pat. Nos. 6,447,123,6,193,378 and 6,816,297 hereby incorporated in their entireties byreference, the first surface coating will have a reflectancesubstantially lower than the reflectance of the preferred embodiments ofa second surface spectral filter material as described herein. This willresult in the hue and/or chroma of the color of the perimeter of thedevice being more dependent on the second surface coatings than those onthe first surface. Nonetheless, especially when color is chosen near apoint of transition from perceived yellowish to bluish, +b* to −b*,respectively, or reddish to greenish, +a* to −a*, respectively, thesedifferences tend to become more perceivable. When attempting to matchthe hue of the spectral filter material to that of the overall field ofview of the reflector, small differences in the materials that result intransitions from more yellow to less yellow, or less blue to more blue,when compared to the overall field of view of the element may be avoidedby practicing the teachings herein. A similar contrast in reddish orgreenish hue may be managed.

For example, the color and reflectance of the ring and viewing area withand without a hydrophilic surface coating were modeled with a thin filmprogram. The spectral filter ring consists of 126 nm of ITO, 3 nm of Cr,5 nm of Rh, 30 nm of Ru and 40 nm of Cr. The exit medium or materialnext to the metals and dielectric layers is an electrochromic fluid withan index of approximately 1.365. The hydrophilic layer consists of a 65nm color suppression layer next to the glass, a 234 nm TiO2 layer with asurface morphology and 10 nm of SiO2.

Table 4a shows the reflectance and color of various portions of themirror. The first two rows show the effect of the presence or absence ofthe hydrophilic layer on the appearance of the ring. The color andreflectance are essentially unchanged with the application of thehydrophilic layer on the first surface of the mirror. In rows 3 and 4 wesee the change of color in the viewing area when the mirror is in thedarkened state. In the undarkened state the higher reflectance of theback reflector dominates the appearance. The reflectance increases withthe hydrophilic layer which may have advantages in certain markets. Thecolor of the viewing area without the hydrophilic layer in this case issomewhat objectionable because the thickness of the ITO is selected tooptimize the color of the ring. This results in a somewhat compromisedcolor in the viewing area. By adding the hydrophilic coating on surfaceone, the color becomes more neutral, a positive benefit to thecombination. The fifth row shows the color of the hydrophilic layerwithout any other coatings on surface two of the glass and with anelectrochromic fluid as the exit medium for reference.

TABLE 4a Color and reflectance of different mirror components StructureR a* b* Hydro/Glass/ITO/Cr/Rh/Ru/Cr 58.46 −4.20 3.23Glass/ITO/Cr/Rh/Ru/Cr 58.23 −4.20 1.96 Hydro/Glass/ITO 13.50 0.69 −3.10Glass/ITO 5.65 4.69 1.92 Hydro/Glass 12.47 −1.70 −4.60

Example Mirror Element Description

A particularly advantageous element configuration in conformance withFIGS. 4 a-4 c and 5 comprises a first substrate of glass approximately1.6 mm thick having a conductive electrode approximately 0.4 wavelengths(approximately 80 percent of half-wave) thick of indium-tin-oxideapplied over substantially the entire second surface by sputtering. Atleast a portion of the first corner, the edge and the second corner aretreated such that approximately 0.25 mm of material is removed from thesecond surface and approximately 0.5 mm of material is removed from thefirst surface. It should be apparent that a portion of conductiveelectrode is removed during treatment. A spectral filter materialapproximately 400 Å thick of chrome is applied approximately 4.5 mm widenear the perimeter of the first substrate proximate the conductiveelectrode. An electrical conduction stabilizing material approximately100 Å thick of a platinum group metal (PGM) (i.e., iridium, osmium,palladium, platinum, rhodium, and ruthenium) is applied approximately2.0 cm wide near the perimeter of the first substrate proximate thespectral filter material. A first separation area is laser etchedapproximately 0.025 mm wide with a portion thereof extending parallelto, and within the width of, a portion of a primary seal material areato substantially electrically insulate the first and second conductiveelectrode portions, spectral filter material portions and adhesionpromotion material portions. A second substrate of glass approximately1.6 mm thick having a conductive electrode approximately 0.5 wavelengthsthick over substantially all of the third surface is provided. A secondseparation area is laser etched approximately 0.025 mm wide with aportion thereof extending parallel to, and within the width of, aportion of a primary seal material to substantially electricallyinsulate the third and fourth conductive electrode portions. Areflective material approximately 400 Å thick of chrome is appliedproximate the third conductive electrode portion substantially definedby the inboard edge of the primary seal. An optional overcoatapproximately 120 Å thick of ruthenium is applied proximate thereflective material substantially defined by the inboard edge of theprimary seal. A primary seal material, comprising an epoxy having acycloaliphatic amine curing agent and approximately 155 μm substantiallyspherical glass balls, is provided to secure the first and secondsubstrates together in a spaced apart relation to define a chamber. Asubstantially rigid polymer matrix electro-optic medium, as taught inmany commonly assigned U.S. Pat. Nos. 5,679,283, 5,888,431, 5,928,572,5,940,201, 6,545,794, and 6,635,194, the disclosures which areincorporated in their entireties herein by reference, is providedbetween the first conductive electrode portion and the optional overcoatmaterial within the chamber through a plug opening in the primary sealmaterial. The plug opening is sealingly closed using ultra-violet lightcurable material with UV light irradiating the plug bottom through thethird and fourth surface. The cured primary seal material and the plugmaterial are inspected by viewing the element looking toward the fourthsurface. An electrically conductive material comprising a bisphenol Fepoxy functional resin, viscosity of approximately 4000 cP having acycloaliphatic amine curing agent, viscosity of approximately 60 cP, anda silver flake, tap density approximately 3 g/cc and average particlesize of approximately 9 μm is applied proximate the outboard edge of theprimary seal material between the second adhesion promotion materialportion, the third conductive electrode portion and the first electricalclip. This same electrically conductive material is applied proximatethe outboard edge of the primary seal material between the firstadhesion promotion material portion, the fourth conductive electrodeportion and the second electrical clip. A double sided, pressuresensitive, adhesive material is provided between the electrical clip andthe fourth surface of the second substrate. The electrically conductivematerial is cured after placement of the first and second electricalclips. The primary seal material is partially cured prior to applicationof the electrically conductive material; additional primary sealmaterial curing coincides with curing the electrically conductivematerial. This curing process is beneficial to prevent warping of theelement and improves overall related adhesion, sealing and conductivitycharacteristics. This example mirror element description is provided forillustrative purposes and in no way should be construed to limit thescope of the present invention. As described throughout this disclosure,there are many variants for the individual components of a given elementand associated rearview mirror assembly.

In embodiments of the present invention having a highly reflectivespectral filter material applied between the second surface of the firstsubstrate and the primary seal, it has proven advantageous to usespecifically selected spacer material to eliminate bead distortion.Glass beads are typically added to the primary seal material to controlthe spacing between the substrates that form the chamber containing theelectro-optic medium. The diameter of preferably substantiallyspherically shaped glass beads is a function of the desired “cell”spacing.

These glass beads function well as spacers in electro-optic devices thathave two transparent substrates, a transparent front substrate and areflector positioned on surface three or four. These spacers alsofunction well in devices with a spectral filter material on the firstsurface or within the first substrate. However, when the spectral filtermaterial is applied proximate the primary seal material and the secondsurface, “dimples”, or small distortions in the chrome spectral filtermaterial, are created by typical glass spacer beads and are visible inthe seal area of a resulting mirror element. These dimples are alsovisible in mirror elements having a third surface reflector; however,they can only be seen if the mirror element is viewed looking at thefourth surface. These third surface dimples in a reflector are notvisible in a resulting mirror element when viewed once installed in avehicle.

In contrast, these dimples are readily visible in a resulting mirrorelement when the spectral filter material is proximate the secondsurface and covers the primary seal material area. These dimples arecreated, at least in part, by high stress areas proximate the glassspacer beads. Typically, the primary seal material comprises asubstantially rigid thermal curing epoxy; preferably comprising acycloaliphatic amine curing agent. The curing temperature of the epoxymaterial is often greater than 150 degrees Centigrade. There is often asignificant difference in thermal expansion between the customarily usedceramic glass bead (low coefficient of thermal expansion) and the epoxymaterial (high coefficient of thermal expansion). At least a portion ofthe glass spacer beads are in contact with the top material of arespective stack of materials proximate the second and third surfaces ofthe substrates when the seal solidifies and cures at high temperatures.As the mirror element cools in the post primary seal material curecycle, the seal material shrinks much more than the spacer beads andstress develops around the bead creating a distorted area, or dimple, inthe substrate stack. When the substrate comprises a reflector on asurface that is in contact with the primary seal material, thesedistorted areas or dimples are visually perceptible.

These distorted areas can be eliminated in a number of ways. A moreelastomeric or flexible primary seal material may be used thatinherently does not build areas of high stress. A spacer that is morecompressible may be used such that the spacer flexes as stress develops.A breakable spacer may also be used such that the spacer breaks torelieve the localized stress during primary seal material curing. A roomor low temperature curing seal material with low cure shrinkage may beused that will eliminate or minimize the thermal expansion-relatedstress. A seal material and spacers that are a closer match in thermalexpansion may be used to eliminate or minimize the thermalexpansion-related stress, such as plastic spacer beads and plastic sealmaterial, ceramic spacer beads and ceramic seal material or sealmaterial and/or spacer beads containing a thermal expansion modifyingfiller. The spacer beads in the seal material may be eliminatedaltogether if proper methods of element manufacturing are used tocontrol the element gap (“cell” spacing). For example, a spacing media,such as a PMMA bead or fiber that dissolves in the electro-optic media,could be applied to the area internal the primary seal to control theelement gap during primary seal material curing. The element substratesmay also be held apart mechanically until the seal solidifies.

Example 1 Primary Seal with Spacers

A master batch of thermal cure epoxy was made using 96 parts by weightDow 431 epoxy novolac resin, 4 parts fumed silica and 4 parts 2 ethyl 4methyl imidazole. To small portions of the above master batch 2 parts byweight of the following spacer materials were added. A dab of theepoxy/spacer mixture was then put on a 1″×2″×0.085″ thick piece ofchrome coated glass such that the epoxy mixture was in contact with thechrome reflector. A 1″×1″×0.85″ piece of ITO coated glass was placed ontop and the glass sandwich was clamped such that the glass piecesbottomed out to the spacer material. The element was then cured at about180 degrees Centigrade for about 15 minutes. Subsequently, once theelement returned to room temperature, it was visually inspected fordimples looking at the chrome as if it were on surface two.

Example 2 Primary Seal Material

Using the thermal cure epoxy of Example 1 plus 140 um Glass Beads causeda very heavy dimple pattern to be visible.

Example 3 Primary Seal Material

Using the thermal cure epoxy of Example 1 plus Plastic Beads(Techpolymer, Grade XX-264-Z, 180 um mean particle size, SekisuiPlastics Co. Ltd., Tokyo, Japan) caused no dimple pattern to be visible.

Example 4 Primary Seal Material

Using the thermal cure epoxy of Example 1 plus Plastic Fibers (Trilene,140 um diameter monofilament line cut to 450 um lengths, Berkley, SpringLake, Iowa) caused no dimple pattern to be visible.

Example 5 Primary Seal Material

Using the thermal cure epoxy of Example 1 plus Hollow Ceramic Beads(Envirospheres, 165 um mean particle size, Envirospheres PTY Ltd.,Lindfield, Australia) caused very slight, but acceptable, dimple patternto be visible.

Example 6 Primary Seal Material

Using an epoxy cured at room temperature caused no dimple pattern to bevisible after 1 week at room temperature.

Example 7 Primary Seal Material

Using two parts by weight glass beads (140 um) added to a UV curableadhesive, Dymax 628 from Dymax Corporation, Torrington, Conn., andcompressing the adhesive between two glass substrates as described abovecaused a very slight, but acceptable, dimple pattern to be visible. Theadhesive was UV cured at room temperature.

Turning to FIGS. 7 a-n, there are shown various options for selectivelycontacting a particular portion of the second and third surfaceconductive electrode portions 705, 710. As can be appreciated, theconfiguration of FIG. 5 results in the electrically conductive materialcontacting at least a portion of each of the second and third surfaceconductive electrode portions.

The element construction depicted in FIG. 7 a comprises a firstsubstrate 702 a having a second surface stack of materials 708 a and asecond substrate 712 a having a third surface stack of materials 722 a.The third surface stack of materials is shown to have an isolation area783 a such that a portion of the third surface stack of materials thatis in contact with a conductive epoxy 748 a is isolated from theremainder of the third surface stack of materials. The first and secondsubstrates are held in spaced-apart relationship to one another via aprimary seal material 778 a. It should be understood that another sideof the element may have a similar isolation area associated with thesecond surface stack of materials for providing contact to the thirdsurface stack of materials within the viewing area. It should beunderstood that either the second or third surface stack of materialsmay be a single layer of on materials as described elsewhere herein andwithin references incorporated herein by reference.

The element construction depicted in FIG. 7 b comprises a firstsubstrate 702 b having a second surface stack of materials 708 b and asecond substrate 712 b having a third surface stack of materials 722 b.The first and second substrates are held in a spaced-apart relationshipwith respect to one another via a primary seal material 778 b. Anelectrically conductive epoxy 748 b is in contact with the third surfacestack of materials and electrically insulated from the second surfacestack of materials via the insulating material 783 b. It should beunderstood that another side of the element may have a similar isolationarea associated with the second surface stack of materials for providingcontact to the third surface stack of materials within the viewing area.It should be understood that either the second or third surface stack ofmaterials may be a single layer of on materials as described elsewhereherein and within references incorporated herein by reference.

The element of FIG. 7 c comprises a first substrate 702 c having asecond surface stack of materials 708 c and a second substrate 712 chaving a third surface stack of materials 722 c. The first and secondsubstrates are held in spaced apart relationship with respect to oneanother via a primary seal material 778 c. The second surface stack ofmaterials extends toward the edge of the first substrate beyond theprimary seal material such that it is in electrical contact with a firstelectrically conductive epoxy or first solder 748 c 1. The third surfacestack of materials extends toward the edge of the second substratebeyond the primary seal material such that it is in electrical contactwith a second electrically conductive epoxy or second solder 748 c 2. Itshould be understood that another side of the element may have a similarisolation area associated with the second surface stack of materials forproviding contact to the third surface stack of materials within theviewing area. It should be understood that either the second or thirdsurface stack of materials may be a single layer of on materials asdescribed elsewhere herein and within references incorporated herein byreference.

FIG. 7 d depicts the second surface electrical contact 748 d 1 beingmade on an opposite side of the element from a third surface electricalcontact 748 d 2. FIG. 7 e depicts the second surface electrical contact748 e 1 being made on a side of the element and the third surfaceelectrical contact being made on an end of the element. FIG. 7 f depictsthe second surface electrical contact 748 f 1 being made on one side andcontinuously with one end of the element and the third surfaceelectrical contact 748 f 2 being made on an opposite side andcontinuously with an opposite end of the element. FIG. 7 g depicts thesecond surface electrical contact 748 g 1 being made on opposite sidesof the element and the third surface electrical contact 748 g 2 beingmade on an end of the element. FIG. 7 h depicts the second surfaceelectrical contact 748 h 1 being made on opposite sides of the elementand the third surface electrical contact 748 h 2 being made on oppositeends of the element. FIG. 7 i depicts the second surface electricalcontact 748 i 1 being made continuously on opposite ends and one side ofthe element and the third surface electrical contact 748 i 2 being madeon one side of the element. It should be understood that, in at leastone embodiment, the longer electrical contact will correspond to thesurface having the highest sheet resistance stack of materials. Itshould be understood that the electrical contact may be via electricalconductive epoxy, solder or an electrically conductive adhesive.

FIG. 7 j depicts an element comprising a first substrate 702 j having asecond surface stack of materials 708 j and a second substrate 712 jhaving a third surface stack of materials 722 j. The first and secondsubstrates are held in spaced apart relationship with respect to oneanother via perimeter first and second primary seals 748 j 1, 748 j 2.The first primary seal functions to make electrical contact with thesecond surface stack of materials and the second primary seal functionsto make electrical contact with the third surface stack of materials.The first and second primary seals hold the first and second substratesin a spaced apart relationship with respect to one another andpreferably both primary seals are substantially outside the edge of eachsubstrate.

With reference to FIG. 7 k, a profile view of a portion of a rearviewmirror element is depicted comprising a first substrate 702 k having atleast one layer 708 k of a substantially transparent conductive materialdeposited on the second surface and a second substrate 712 k having astack of materials deposited on the third surface secured in a spacedapart relationship with respect to one another via a primary sealmaterial 778 k to define a chamber there between. In at least oneembodiment, an electro-optic medium 710 k is located within saidchamber. In at least one embodiment, the third surface stack ofmaterials comprises an underlayer 718 k, a conductive electrode layer720 k, a metallic layer 722 k and a conductive tab portion 782 k havingan overlap portion 783 k underneath the metallic layer and primary sealmaterial. It should be noted that the conductive tab portion 782 k couldalternatively be deposited over the metallic coating 722 k to create theoverlap portion. In at least one embodiment, the underlayer istitanium-dioxide. In at least one embodiment, the underlayer is notused. In at least one embodiment, the conductive electrode layer isindium-tin-oxide. In at least one embodiment, the conductive electrodelayer is omitted. In at least one embodiment, the conductive electrodelayer emitted and the underlayer is either a thicker layer oftitanium-dioxide or some other substantially transparent material havinga relatively high index of refraction (i.e., higher index of refractionthan ITO), such as, silicon carbide. In at least one embodiment, theconductive tab portion comprises chrome. It should be understood thatthe conductive tab portion may comprise any conductive material thatadheres well to glass and is resistant to corrosion under vehicularmirror testing conditions. As can be appreciated, when the third surfacestack of materials, or at least those layers within the stack that aresusceptible to corrosion, are kept within an area defined by an outeredge of the primary seal material, the element will be substantiallyimmune to problems associated with third surface corrosion. It should beunderstood that the layer, or layers, susceptible to corrosion mayextend beyond the primary seal material provided a protective overcoator sealant is incorporated, such as, conductive epoxy or an overcoatlayer. It should be understood that any of the first, second, third andfourth surface layers or stacks of materials may be as disclosed hereinor within the references incorporated elsewhere herein by reference. Itshould be understood that the conductive tab portion improvesconductivity over the conductive electrode; as long as a conductiveelectrode layer is provided with sufficient conductivity, the conductivetab portion is optional. In at least one embodiment, the conductiveelectrode layer imparts the desired color specific characteristics ofthe corresponding reflected light rays in addition to providing thedesired conductivity. Therefore, when the conductive electrode isomitted, color characteristics are controlled via the underlayermaterial specifications.

Turning to FIG. 71, a profile view of a portion of a rearview mirrorelement is depicted comprising a first substrate 702 l having at leastone layer 708 l of a substantially transparent conductive materialdeposited on the second surface and a second substrate 712 l having astack of materials deposited on the third surface secured in a spacedapart relationship with respect to one another via a primary sealmaterial 778 l to define a chamber there between. In at least oneembodiment, an electro-optic medium 710 l is located within saidchamber. In at least one embodiment, the third surface stack ofmaterials comprises an underlayer 718 l, a conductive electrode layer720 l, a metallic layer 722 l and a conductive tab portion underneaththe primary seal material. In at least one embodiment, a void area 783 lis defined between the metallic layer and the conductive tab portion,the conductive electrode provides electrical continuity there between.In at least one embodiment, the underlayer is titanium-dioxide. In atleast one embodiment, the underlayer is not used. In at least oneembodiment, the conductive electrode layer is indium-tin-oxide. In atleast one embodiment, the conductive tab portion comprises chrome. Itshould be understood that the conductive tab portion may comprise anyconductive material that adheres well to glass and is resistant tocorrosion under vehicular mirror testing conditions. As can beappreciated, when the third surface stack of materials, or at leastthose layers within the stack that are susceptible to corrosion, arekept within an area defined by an outer edge of the primary sealmaterial, the element will be substantially immune to problemsassociated with third surface corrosion. It should be understood thatany of the first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

With reference to FIG. 7 m, a profile view of a portion of a rearviewmirror element is depicted comprising a first substrate 702 m having atleast one layer 708 m of a substantially transparent conductive materialdeposited on the second surface and a second substrate 712 m having astack of materials deposited on the third surface secured in a spacedapart relationship with respect to one another via a primary sealmaterial 778 m to define a chamber there between. In at least oneembodiment, an electro-optic medium 710 m is located within saidchamber. In at least one embodiment, a first metallic layer 718 m isdeposited over substantially the entire third surface. In at least oneembodiment, a second metallic layer 720 m is deposited over the firstmetallic layer such that an outer edge of the second metallic layer islocated within an area defined by an outer edge of a primary sealmaterial 778 m. In at least one embodiment, the first metallic layercomprises chrome. In at least one embodiment, the second metallic layercomprises silver or a silver alloy. It should be understood that any ofthe first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

Turning to FIG. 7 n, a second substrate 712 n is depicted comprising astack of materials having an eyehole 722 n 1 substantially in front of alight sensor or information display. In at least one embodiment, a firstmetallic layer 718 n is provided with a void area in the eyehole area.In at least one embodiment, a second metallic layer 720 n is providedwith a void area in the eyehole area. In at least one embodiment, athird metallic layer 722 n is provided. In at least one embodiment, onlythe third metallic layer is deposited in the eyehole area. In at leastone embodiment, the first metallic layer comprises chrome. In at leastone embodiment, the second metallic layer comprises silver or silveralloy. In at least one embodiment, the third metallic layer comprises athin silver, chrome or silver alloy. It should be understood that any ofthe first, second, third and fourth surface layers or stacks ofmaterials may be as disclosed herein or within the referencesincorporated elsewhere herein by reference.

One way the spectral filter material 715, proximate a first surfaceconductive electrode, can be electrically insulated from otherconductive electrode portions is by overcoating at least portions of thespectral filter material with an organic or inorganic insulatingmaterial as depicted in FIG. 7 b.

When a spectral filter material, such as chrome metal, is applied on topof the transparent conductor of the second surface through a mask in acoating operation (such as by vacuum sputtering or evaporation, etc.), anon-conductive coating may be applied through a mask in the same processto electrically isolate the second surface conductive electrode from thethird surface conductive electrode in the conductive seal area.

Example 1: Insulating material: a spectral filter material comprisingmetal, metal alloy, layers of metals, layers of metal alloys orcombinations thereof, such as chrome, molybdenum, stainless steel, oraluminum, rhodium, platinum, palladium, silver/gold, white gold andruthenium, often over an adhesion promotion material such as chrome, isvacuum deposited through a mask over a transparent conductor (such asITO) to cover the seal area. An insulating material such as silicon,silicon dioxide, chromium oxide, aluminum oxide, titanium oxide,tantalum oxide, zirconium oxide, or yttrium oxide can be applied withuse of a mask over the top of the metal layer to electrically isolatethe desired spectral filter material area from other conductiveportions. This electrical insulation material is not applied to, orremoved from, portions of the spectral filter material oradmission/conductivity promotion material where electrical conductivityis desired.

One method to reduce the size of, or to eliminate the need for, thebezel is to make an element with substantially no offset between theperipheral edges of the first and second substrates using anelectrically conductive material as a portion of the electrical bus. Inorder to use the preferred electrically conductive material, anisolation of a portion of the conductive materials on the second and/orthird surfaces needs to take place. The second and third surfaces wouldbe shorted together by the electrically conductive material if oneportion of each surface were not isolated in non-overlapping areas. Thethird surface may be electrically isolated on one side of the elementand the second surface would be electrically isolated on an opposite oradjacent side of the element. Preferably, a laser is employed to removeconductive material from the desired areas. The laser separation ispreferably located between the electrically conductive material and thevisibly active area of the element. More preferably the separation areais located such that an anode and cathode are not coexistent on the samesurface and in contact with the electro-optic medium. When an anode andcathode are located on the same surface with the addition of an anode ora cathode on the adjacent surface, a residual slow to erase color willbe present along the separation area. Additionally, with an anode on thesecond surface and the third surface between the seal and the separationarea, the color produced by the anode is visible between the primaryseal material and the separation area. Likewise, if a cathode is locatedon the third surface and the second surface between the primary sealmaterial and the separation area, the color produced by the cathode isvisible from the front between the separation area and the primary sealmaterial.

In mirror elements having a spectral filter material between the viewerand the primary seal material, a separation area may be incorporated.With the spectral filter material on the first surface, the mirrorelement is made much the same as described with regards to elements thatdo not include a spectral filter material. The separation areas are notvisible when looking at the first surface. When the spectral filtermaterial is proximate the second surface, the separation area is visiblewhen looking at the first surface.

A typical laser defined separation area is between 0.005-0.010 incheswide. By making the separation area 0.002-0.004 inches wide, it is muchless noticeable. Even more preferable would be an isolation line of lessthan 0.002 inches so as to be virtually unnoticeable from the driver'sperspective. Material can be removed to create an electrical isolationline using a variety of techniques including masking during coatingdeposition, media blasting, laser ablation, mechanical abrasion,chemical etching, or other methods known in the art. Photolithography incombination with chemical, reactive ion or other etching method couldproduce isolation lines below 1 um in width. It should also be notedthat shorter wavelength lasers can be focused to create a smaller spotsize. This provides for a more narrow and less visible electricalisolation line. As the isolation line becomes more narrow, it may becomeincreasingly difficult to achieve complete electrical isolation betweenthe first and second conductive portions. The resistance between the twoconductive portions can be easily measured using an ohmmeter. For atypical electro-optic mirror element, it is preferred that thisresistance is greater than 30 ohms. It is more preferred that thisresistance is greater than 100 ohms. Complete electrical isolation ismost preferred. The separation area is preferably located within theprimary seal material area and extends the length of the element toprovide a large electrical contact area. When the separation area islocated over the top of the primary seal material area, the color ortransparency of the seal can be adjusted to help hide the separationarea. This separation area may be incorporated into artwork or text onthe mirror element. A separation area may be incorporated into adisclaimer on the mirror element, a manufacturer's emblem, or othergraphic and/or text. It should be understood that the laser line may bepositioned along the inner edge of the spectral filter material. In thisconfiguration, the majority of the laser line is not visible because thelaser line coincides with the edge of the spectral filter material. Someresidual color is present after clearing the electro-optic media on thesame substrate; however, most of the colored area is hidden from viewbehind the spectral filter material. The only laser line portions thatare visible are short line segments made through the spectral filtermaterial near the edge in two places.

It is also generally desirable to position the electrode isolation line,such as a laser ablation line in an area of the mirror, outside of thespecified field of view of the mirror. There are legal guidelines in theUnited States, Europe and in other countries for the minimum area to theside and rear of a vehicle that must be visible in a mirror. This areacan be projected onto the surface of the mirror and objects that arewithin the boundaries of that projection must be visible to the driver.This projection generally takes the shape of a triangle and the size ofthe projection can be larger or smaller depending on whether the mirrorsurface is flat or bent. FIG. 2 a details the shape (identified withdashed line 211 a) of a typical specified minimum field of viewprojection for a left hand outside electrochromic mirror with a bezel.Since the bezel area is not reflective it cannot be included in thefield of view of the mirror. However, the bezel area can be covered witha spectrally reflective coating such as a metallic ring on surface two.As long as this reflective ring has a high enough reflectance to meetthe minimum reflectance standards for the particular country, this areacould be considered field of view. As described previously, the mirrorcould then be made smaller by the bezel width while maintaining the samespecified field of view. Again, it would be preferable to locate anyvisible electrode isolation lines outside of the projection of thespecified field of view of the mirror.

Another way to isolate the electrically conductive material is to use anonconductive layer between the electrically conductive material and thesurface to be isolated, such as a vacuum deposited dielectric ink, or athinned layer of a nonconductive epoxy or other resin. It may bedesirable to employ a separation area proximate the third surfacebecause the separation area is not visible looking at the first surface.By using a nonconductive material on the second surface, there is noneed for a first separation area. This is particularly desirable whenthe second surface has a spectral filter material. By thinning anonconductive epoxy, a very thin layer can be obtained. This isimportant because enough area needs to be provided to apply theelectrically conductive material. Preferably, the nonconductive epoxy isonly flash cured. For example, place the material in an 85 c oven forapproximately two minutes. If the nonconductive epoxy is fully cured andis partially covering an area that is in contact with the primaryassociated spacer beads, an undesirable, non-uniform cell spacing may becreated. By not curing the nonconductive material completely, the spacerbeads will more easily penetrate the layer during the final cure, andnot affect the cell spacing.

An external electrical connection may be made to the third surface of anelectro-optic mirror element having a second surface spectral filtermaterial by extending at least a portion of the third surface conductiveelectrode under the primary seal material area and over the perimeteredge of the second substrate. When coating (such as by vacuumsputtering) over the edge of a piece of glass, the conductivity of thecoating tends to decrease over a sharp edge or rough surface. Also, thecoating process does not typically provide a durable coating on the sideor edge of the glass. To do this without losing conductivity, a goodseam or polish on the substrate corner and/or edge is helpful to providea smooth transition from the third surface to the edge. A rough groundsurface without polishing has lower conductivity at a typical thirdsurface coating thickness. The smoother the surface and transition fromthe third surface to the edge, the better the conductivity. A sputtertarget mounted to coat the edge of the glass during the coating processis also helpful to provide a more uniform and durable coating.

It is conceivable that the coating could be extended over the edge ofthe glass and onto the back of the glass such that the electricalconnection to the third surface could be made on that back of the mirrorelement. A reflective third surface is typically more conductive than asecond surface conductive electrode; therefore, an electricallyconductive material may not be needed. Therefore, the primary sealmaterial may be dispensed up to the edge of the substrate. Having thethird surface material extending onto the edge may only be on one side.The opposite substrate may comprise a separation area and electricallyconductive material to the third surface since it is not visible.

With the third surface material extended onto the edge of the substrate,an L clip in lieu of a J clip can be used since there is no need to havea clip portion inserted between the second and third surfaces. The Lclip only needs to be long enough to contact the conductive portion onthe edge. A conductive epoxy could be used to bond to the third surfacematerial on the edge to the L clip. A pressure sensitive adhesive couldbe used on the back of the L clip to secure it to the fourth surface.Alternatively, solder could be applied directly to the coating on theedge or back of the mirror. In one embodiment, the solder could be usedas both the contact and as a conductive bus system.

One advantage of making external electrical contact to the third surfacematerial extended onto the edge of the substrate is that a conductivematerial is no longer required adjacent to the primary seal for filtermaterial on the first or second surface may be narrower while stillcovering the primary. Although a typical spectral filter material mayvary from 4 to 8 mm in width, it may be aesthetically pleasing to reducethis width below 4 mm. As the width of the primary seal is reduced, thewidth of the spectral filter material may also be reduced. Usingassembly and sealing techniques previously disclosed, it is possible toreduce the primary seal with to less than 1 mm which allows for aspectral filter width of less than 1 mm.

Another way to make electrical connection to the third surface isolatedfrom the second surface is to use a conductive ink or epoxy to connectthe third surface to the edge. Thinning the conductive ink or epoxy andapplying it to the edge of the substrate contacts the third surfacewithout contacting the second surface. With this thinned conductiveepoxy, a conductive path can be applied such that contact is made on theedge or the back of the mirror element. An L clip may be applied contactand cured in place. A pressure sensitive adhesive may be used to securethe L clip in place during the curing process and to provide strainrelief with connecting wires.

If the corrosive effects of the environment on the metal can beminimized, very thin metal films or foils can be used to establish astable interconnect to the conductive adhesive or bus. This metal foilor metal film on a plastic foil could be conformed to the shape of the Jclip or other desired shape (without the need of expensive forming dies)and adhered to the substrate with an adhesive such as a pressuresensitive. This metal foil or metal film on plastic foil may be in theform of a roll of adhesive tape that is cut to size and applied to theEC element substrate such that one end comes in contact with theconductive bus that is in contact with the front and/or backelectrode(s). A spade connect or wire may be attached to the other endof the metal foil or film by traditional methods such as soldering orconductive adhesive, or the end of the metal foil or tape may connectdirectly to the voltage source for the EC element such as a printedcircuit board.

At least one embodiment of a formable contact comprises 0.001″ palladiumfoil (Aldrich chemical Milwaukee, Wis.) laminated to 0.002″ acrylicdouble-sided adhesive tape with a release liner (product 9495 200MPseries adhesive 3M Corporation, Minneapolis, Minn.). The metal foil tapemay be cut to an acceptable size for application on an electrochromicdevice. The metal foil or metal film on plastic foil tape may also beprecut to a form or shape if desired.

At least one embodiment of a formable contact may be made from a plasticfilm and metallized with a metal such as gold, silver, titanium, nickel,stainless steel, tantalum, tungsten, molybdenum, zirconium, alloys ofthe above, or other metals or metal alloys that resist salt spraycorrosion. Also, palladium or other platinum group metals such asrhodium, iridium, ruthenium, or osmium may be used.

At least one embodiment of a formable contact uses a polymer carriercomprising 0.002″ polyimide tape (#7648A42 McMasterCarr, Chicago, Ill.)coated with chrome and with any platinum group metal such as rhodium,indium, ruthenium, or osmium as the base, and then coated with a layerof silver, gold or alloys thereof. This system is solderable and hassufficient flexibility to wrap around the glass edge from one substratesurface to another surface.

At least one embodiment comprises a conductive coated polymer filmproduced for the flexible circuit industry such as In at least oneembodiment, Sheldahl (Northfield, Minn.) produces combinations ofpolyimide (Kapton) and polyester films coated with ITO, aluminum,copper, and gold. Polyimide tapes coated with a base metal may be platedor coated with different metals or alloys to improve durability and/orsolderability. These films can be coated with an adhesive or laminatedto double-sided tape as described above. This metallized foil can bebent around a glass edge and maintain good conductivity.

At least one embodiment using a fibrous substrate is comprised of asolvent-based ink placed onto a fiber backing. The conductive ink iscomprised of 10 parts methyl carbitol (Aldrich Milwaukee, Wis.), 2 partsBis A-epichlorhydrin copolymer (Aldrich Milwaukee, Wis.), and 88 partsof LCP1-19VS silver epoxy flake. The conductive ink may be applied tofibrous material such as those comprising glass, metal, or cellulose.The system is heated sufficiently to evaporate the solvent. Theconductive and flexible formable contact is then applied to one surface,wrapping around to another surface.

At least one embodiment of a polymeric formable contact incorporates aconstruction mechanism to either protect the metal, hide the metalcolor, or offer another color more appealing to the outside appearanceof the glass edge. This construction would incorporate a polymeric filmon the outside, followed inwardly by the metal coating, and followedinwardly by an adhesive. The metal coating within the system would needto have an exposed edge for making contact to one of the glass insideconductive surfaces. Contact to this end could be made with an appliedconductive adhesive, solder, or other method to make a stable electricalcontact. The opposite end could have contact made with conductiveadhesive, solder, or other mechanical means.

In relation to the conductivity of a conductive polymer or composite,there are methods to describe the conductive polymer or composite'sconductivity. Those skilled in the art of isotropic and anisotropicconductive adhesives commonly use a 4-pin probe for the resistancemeasurement. A common unit of measurement in the field of conductiveadhesives is ohms/square/mil. This measurement is expressed as not onlya factor of width, but also of thickness. This measurement, whenperformed on a nonconductive substrate, expresses the linearconductivity of a conductive polymer or composite such as a metal orcarbon or metal oxide conductive particle-filled epoxy.

Another method by which to determine conductive polymer effectivenessfor use as a bus is to utilize isolated conductive pads and bridge theseisolated pads using the conductive polymer. A particular way to performthis test is to isolate conductive coatings on glass with laserablating, physical scoring, or chemical removal. The uncured conductivepolymer is applied to bridge the conductive pads so that the currentpath must pass through multiple contact interfaces, but is stillisolated from itself so as to not short the bridges together. Aresistance reading is taken at the ends across the test piece.

Not all conductive polymers with high conductivity measured by theohm/sq/mil method have adequate interfacial electric contact to theelectrode surfaces used in an electrochromic device. Based on the abovecoupon using an ITO electrode as the isolated conductive pad, anacceptable resistance would be less than 1000 ohms. A more preferredresistance is less than 500 ohms, and an even more preferred resistanceis less than 200 ohms.

There are methods to affect this interfacial conductivity through theselection of conductive polymer components. The shape of the metalpowder or flake can affect the interfacial contact. Additives can alsoaffect the interfacial contact. Coupling agents, curing catalysts orcross linkers, epoxy resin systems, and methods by which to process thesilver epoxy can have an affect on the conductive polymer's ability tomake electrical contact to an adjacent conductive surface.

In at least one embodiment, a silver epoxy comprises 3 partsHexahydrophthalic anhydride (Aldrich, Milwaukee, Wis.), 2.14 partsAniline glycidyl ether (Pacific Epoxy Polymers), 0.1 parts Benzyldimethyl amine (Aldrich chemical, Milwaukee. Wis.), and 23.9 partssilver flake LCP1-19VS (Ames Goldsmith, Glens Falls, N.Y.). When testedusing an ohm/square/mil conductivity measurement, results are acceptable(approximately 0.020 ohm/sq/mil).

In another embodiment, U.S. Pat. Nos. 6,344,157 and 6,583,201 disclosethe use of corrosion inhibitors, oxygen scavengers or metal chelatingagents for use in conductive adhesives.

In some cases, additives can be added to silver epoxies to stabilize orimprove conductivity. In at least one embodiment, a silver epoxycomprising 3.4 parts Bis F epoxy resin (Dow Corporation, Midland, Mo.),1.1 parts (Air Products and Chemicals, Allentown, Pa.), 20.5 partssilver flake (Ames Goldsmith, Glens Falls, N.Y.), and 0.03 partsDiethanolamine (Aldrich, Milwaukee, Wis.). Results are acceptable forboth conductivity (approximately 0.020 ohms/square/mil) and interfacialcontact (approximately 190 ohms).

As mentioned elsewhere in this patent, a sputtered or vacuum-appliedmetal coating can be extended beyond the seal and over the edge of theglass to be used as an electrical connection. The metal coating shouldmeet the criteria of corrosion-resistant metals listed above. Theelectrical connection to this coating could be made with a spring clip,or solder could be applied directly to the metal coating.

At least one embodiment of a solderable metal coating on glass, chromeis coated as the base layer then coated with any platinum group metalsuch as rhodium, irridium, palladium, ruthenium, or osmium, or copper,silver or gold, or alloys of the above are solderable using tin/leadsolders.

In another embodiment, chrome is coated as the base layer, then coatedwith any platinum group metal such as rhodium, irridium, palladium,ruthenium, or osmium, then coated with copper, silver or gold or alloysof the above are solderable using tin/lead solders.

In current automotive construction, restrictions exist using lead-basedcomponents such as solders. Other solders such as tin/zinc tin/silver,indium-based solders containing silver, bismuth, tin, zinc, copper, andor antimony; silver solders or other non-lead containing alloys may beused as a solder material. Soldering systems that may be employed areinductive heat, IR heat, ultrasonic, wave soldering or a soldering iron.

Another advantage to having a thinner conformable conductive bus clipmaterial as an electrical interconnect to the conductive epoxy is toreduce distortion in the reflection of the first substrate particularlywhen the first element is larger than the second element. Distortion canbe generated as a result of high temperature seal curing and differencesin the coefficients of thermal expansion between the seal and theconductive clips. The thicker the clip material, the more distortion isseen, particularly when using more flexible substrates. A thinner clipmaterial also has the advantage of being less noticeable if it is usedto wrap around the 3^(rd) surface to the back of the mirror. This isparticularly relevant if the first and second elements are aligned atthe point the clip wraps around. When the first element extends past thesecond element, the clip can be hidden entirely from view.

Example: An electrochromic mirror was made with flat 1.6 mm thick glassfor both front and rear elements. The front element was cut 0.040″larger (offset) on three sides. The inboard side (the side closest tothe driver) had no offset to facilitate easier filling and plugging ofthe part. A 0.001″×0.5″×0.75″ silver foil with 0.002″ thick pressuresensitive adhesive was applied on the top and bottom of the secondelement. The conformable conductor contacted 0.010″−0.030″ of surfacethree then wrapped around to the fourth surface. A primary seal materialwas then dispensed around the perimeter of the first element leavingapproximately 0.040″ for an offset on three sides and an additional0.040″ between the seal material and the edge of the glass element onboth the top and bottom edge of the second surface of the first element.The second element was then attached to the first element leaving a0.006″ space between the elements. The seal material was cured to fixthe elements in this spaced-apart relationship. After cure of theprimary seal, a conductive epoxy was then injected into the part fromthe edge on the top and bottom of the part, thereby encapsulating andmaking electrical contact with the third surface portion of theconformable conductor. It should be noted that this process ofdispensing a primary seal and a conductive seal could be accomplishedmore readily and easily on a dual dispense system, dispensing bothepoxies at the same time. The conductive epoxy was then cured. Themirror was inspected for distortion of the first surface reflection overthe conformable conductor, and no distortion was found. When similarmirrors were constructed using either nickel, stainless steel or copperclips with a 0.003″ thickness, visual distortion can be seen near theperimeter of the first surface in the area directly above the clip.

As mentioned elsewhere herein, establishing electrical contact to thesecond and third surface conductive electrodes typically involvescoordination of a number of individually designed components. Turning toFIGS. 8 a-i, various options for electrical clips are depicted. Theplacement of the electrical clips is discussed throughout thisdisclosure in concert with the electrically conductive material.

A preferred electrically conductive material comprises 27.0 g Dow 354resin—a bis phenol F epoxy functional resin. Viscosity is preferably˜4000 cP 9.03 g Air Products Ancamine 2049- a cycloaliphatic amine cureagent. Viscosity preferably is ˜60 cP, 164 g Ames Goldsmith LCP 1-19VSsilver—a silver flake with tap density ˜3 g/cc and average particle size˜6 microns.

As described herein, at least one embodiment comprises a perimetermaterial surrounding the periphery of the element. A preferred perimetermaterial comprises 120 g Dymax 429 with some fillers added (i.e., 0.40 g6-24 silver flake available from Ames Goldsmith, 1.00 g silver-coatedglass flake (i.e., Conduct-o-fil available from Potters Industries),12.0 g crushed SK-5 glass filler available from Schott Glass or acombination thereof crushed into a powder and sieved with a 325 mesh).This material can be applied to the mirror edge using a number oftechniques. One technique is to load the material into a 30 cc syringewith a needle (˜18 gage). The needle can be oriented in a verticalposition such that the perimeter material is dispensed with air pressure(<50 psi) onto the edge of the element while the element is beingmechanically rotated on a robot arm or other mechanical device. Theapplied edge material can then be cured with UV light. Complete cure canbe accomplished in 20 seconds or less. A robot may also be employed torotate the part as it is being cured to prevent sagging.

The intent of the perimeter material is to protect the bus components;hide visible components like electrically conductive materials, clips,seals, glass edges; protect the cut edge of glass and offer an appealingvisual appearance of the mirror element. This may also be achieved withuse of conventional plastic bezels, grommets, elastomeric bezels and thelike.

Many different materials (such as epoxy, silicone, urethane, acrylate,rubber, hotmelt) and cure mechanisms can be used for this edgetreatment. The preferred cure method is by UV radiation. If fillers,dyes, or pigments that are partially opaque to UV radiation are used, acombination UV thermal cure can be used. Fillers such as glass orreflective silver aid the penetration of UV light by transmission,scattering or internal reflection, and are preferred for good depth ofcure. Preferably the perimeter material has a gray color or appearancesimilar to that of a ground glass edge or is dark or black in color.Colors may be varied by use of organic dyes, micas, impregnated micas,pigments, and other fillers. A darker, more charcoal appearance may beachieved by selecting different fillers and different amounts of filler.Less crushed glass will darken and flatten the color of the aboveformulation. Use of only crushed glass (or flakes or other glassparticle) with a different refractive index than the edge material resinbinder will give the appearance of a ground glass edge, or rough penciledge. Some additives are denser than the media they are contained in.Fumed silicas can be added to help prevent settling of the heaviercomponents (metal and glass particles); 2 percent by weight of fumedsilica was found to be sufficient in the preferred method.

Other ways to apply the perimeter material to the element edge includeapplying the material with a roll, wheel, brush, doctor bar or shapedtrowel, spraying or printing.

The perimeter edge materials chosen for a vehicular exterior applicationpreferably meet the following test criteria. These criteria simulate theexterior environment associated with a typical motor vehicle: UVstability (2500 kJ in UV weatherometer)—no yellowing or cracking orcrazing of material when exposed to direct UV; heat resistance—little orno color change, no loss of adhesion; humidity resistance—little or nocolor change, no loss of adhesion; thermal-cycling—no loss of adhesion,no cracking; CASS or salt spray—protection of the underlying metalcoatings and conductive epoxy systems; no loss of adhesion and novisible sign of underlying corrosion; and high pressure water test—noloss of adhesion after parts have been tested in previous statedtesting.

The perimeter edge materials chosen for an automotive exteriorapplication preferably meet the following test criteria. These criteriasimulate the exterior environment associated with a typical vehicle: UVstability (2500 kJ in UV weatherometer)—no yellowing or cracking orcrazing of material when exposed to direct UV; heat resistance—little orno color change, no loss of adhesion; humidity resistance—little or nocolor change, no loss of adhesion; thermal-cycling—no loss of adhesion,no cracking; CASS or salt spray—protection of the underlying metalcoatings and conductive epoxy systems; no loss of adhesion and novisible sign of underlying corrosion and high pressure water test—noloss of adhesion after parts have been tested in previously statedtesting.

With further reference to FIGS. 7 a-n, various embodiments forconfiguration of second and third surface electrode contacts are shown.FIGS. 7 a-n depict configurations similar to that discussed elsewhereherein having a first surface stack of materials, a second surface stackof materials, a third surface stack of materials and/or a fourth surfacestack of materials. The word “stack” is used herein to refer tomaterials placed proximate a given surface of a substrate. It should beunderstood that any of the materials as disclosed in commonly assignedU.S. Pat. Nos. 6,111,684, 6,166,848, 6,356,376, 6,441,943, 6,700,692,5,825,527, 6,111,683, 6,193,378, 6,816,297, 7,064,882 and 7,324,261, thedisclosures of which are incorporated herein by reference, may beemployed to define a unitary surface coating, such as a hydrophiliccoating. Preferably, second, third and fourth surface stacks are asdisclosed herein or in commonly assigned U.S. Pat. Nos. 5,818,625,6,111,684, 6,166,848, 6,356,376, 6,441,943 and 6,700,692, the disclosureof each is incorporated in its entirety herein by reference.

FIGS. 7 d-i depict various embodiments for configuration of the anodeand cathode connections to the second and third surface conductiveelectrodes, respectively. Preferably, the sheet resistance of the thirdsurface conductive electrode is less than that of the second surfaceconductive electrode. Therefore, the cathode contact area may besubstantially less than the anode contact area. It should be understoodthat in certain embodiments, the anode and cathode connections may bereversed.

The configuration of FIG. 7 j may be used to construct a no-bezel ornarrow-bezel rearview mirror assembly that does not incorporate aspectral filter. If the perimeter seal and electrode contact means 748 j1, 748 j 2 were both substantially moved to the mirror edge, there isnot a requirement for a spectral filter material to cover theseal/contact area. When this approach to mirror element construction isused, the mirror element darkens substantially completely to theperimeter edge during glare conditions. In this approach most or all ofthe seal and contact area can be substantially moved from the perimeterof mirror substrate one, surface two and substrate two, surface three,to the edges of substrate one and substrate two.

In at least one embodiment, the top edge of the first substrate and thebottom edge of the second substrate were coated with a conductive epoxyto transfer electrical conductivity from the conductive electrode oneach substrate to the substrate edge. The conductive epoxy is preferablyformulated using: 3.36 g D.E.R. 354 epoxy resin (Dow Chemical, Midland,Mo.), 1.12 g Ancamine 2049 (Air Products and Chemicals, Reading, Pa.)and 20.5 g of silver flake with an average particle size of 7 um tapdensity of 3.0-4.0 g/cc was thoroughly mixed into a uniform paste. Thisconductive epoxy mixture was thinned with enough toluene to produce alow viscosity conductive paint that could easily be applied to thesubstrate edge. The coated substrates were put in a 60° C. oven for 15to 20 minutes to evaporate the toluene.

A uniform layer of an epoxy that was sparsely filled with conductiveparticles (Z-axis conductor) was applied to 0.001″ thick copper foil.The Z axis epoxy (5JS69E) was formulated as follows: 18 g of D.E.N. 438,2 g D.E.N. 431 (Dow Chemical, Midland, Mo.), 1.6 g of US-206 fumedsilica (Degussa Corporation, Dublin, Ohio), 6.86 g Ancamine 2049 and10.0 g silver flake FS 28 (Johnson Matthey, Royston, Hertfordshire, UK)was blended into a uniform paste. The silver flake filler had a tapdensity of 2.3 g/cc and an average particle size of 23 um. A cured thinfilm of this epoxy formulation becomes conductive in the z-axis and notin the x or y axis. This z-axis conductive epoxy was thinned with enoughtoluene or THF solvent to produce a viscosity suitable to spread into athin uniform thickness onto the copper foil. The solvent was thenevaporated off in a 60° C. oven for approximately 5 minutes. The epoxyremained slightly tacky after solvent evaporation. The edges of the twosubstrates were aligned with virtually no offset. The gap between thesubstrates was accurately maintained by using precision sized PMMA beadsas spacers. A small piece of Kapton tape approximately 2 mm wide wasused on one end extending across the edges of both substrates and thecell spacing. The Kapton tape would eventually be removed from the cellafter assembly and the Kapton tape area, which was not wetted withepoxy, would be used as a fill port. The copper foil with the z-axisconductive epoxy was then applied to the peripheral edge of the partsuch that the epoxy wetted both substrate edges completely. The elementwas then cured in an oven at 200° C. for 15 minutes. After the cure, asmall separation was made in the copper foil on each side toelectrically isolate the copper foil on the top from the copper foil onthe bottom of the part. The copper foil covering the Kapton tape and theKapton tape were removed. The opening created by the removed Kapton tapewas used to fill the part. The opening was then plugged with a UVcurable adhesive. The opening on the opposite side was also plugged witha UV curable adhesive but before filling.

FIGS. 8 a-n depict various embodiments for configuration of anelectrical clip. Generally, the individual clips are depicted to definesubstantially a “J” shaped cross section.

The embodiment of FIG. 8 a depicts a J-clip 884 a configured toaccommodate an electrical connection post (not shown) fixed thereto. Inat least one embodiment, the first and second electrical clips areconfigured in combination with a carrier plate (as described in detailherein with respect to FIGS. 10 a-c) to form a “plug” type electricalconnector. The J-clip comprises an edge portion 883 a and an innerelement portion 882 a. The inner element portion is configured to bepositioned between a first and second substrate and to be in electricalcontact with an electrically conductive epoxy, solder or conductiveadhesive to make electrical contact with either a second or thirdsurface stack of materials.

FIG. 8 b depicts a series of apertures 885 extending through an innerelement portion 882 b to, at least in part, facilitate a mechanical and,or, electrical contact with an electrically conductive material. TheJ-clip 884 b comprises a wire connection feature 886 b and an edgeportion 883 b. The wire connection feature may be configured to eitheraccommodate a solder or a crimp-type wire connection.

FIGS. 8 c-e depict various J-clip configurations 884 c, 884 d, 884 ecomprising an electrical connection stab 886 c, 886 d, 886 e having afriction fit hole 887 c, 887 d, 887 e. Each J-clip has an edge portion883 c, 883 d, 883 e and an inner element portion 882 c, 882 d, 882 e.FIG. 8 c depicts having a portion 885 c of the J-clip folded such thatthe J-clip is not as long and is taller than the J-clip of FIG. 8 d.FIG. 8 e depicts a series of apertures 881 e extending through a thirdportion of the clip to provide a stress relief area to accommodatevariations in material coefficients of expansion.

FIG. 8 f depicts a raised portion 885 f on a J-clip 884 f along with awire crimp 886 f configured to spatially separate the wire contact areafrom the element. This J-clip comprises an edge portion 883 f and aninner element portion 882 f.

FIG. 8 g depicts a J-clip 884 g comprising a wire crimp 886 g, an edgeportion 883 g and an inner element portion 882 g. FIG. 8 h depicts aJ-clip 884 h comprising a wire crimp 886 h, an edge portion 883 h and aninner element portion 882 h. The inner element portion comprises aseries of apertures 881 h to facilitate enhanced mechanical and/orelectrical contact. FIG. 8 i depicts a J-clip 884 i comprising a wirecrimp 886 i, an edge portion 883 i and an inner element portion 882 i.FIG. 8 j depicts a J-clip 884 j comprising a wire crimp 886 j, an edgeportion 883 j and an inner element portion 882 j.

FIG. 8 k depicts a J-clip 884 k similar to that of FIG. 8 a excepthaving a longer portion for adhering to a substrate. This J-clipcomprises an edge portion 883 k and an inner element portion 882 k.

FIG. 81 depicts a J-clip 884 l having two large apertures 886 l forstress relief along with four bumps 887 l for enhancing electricalconnection placement. This J-clip comprises an edge portion 883 l and aninner element portion 882 l.

FIG. 8 m depicts a J-clip 884 m comprising a wire crimp 886 m, an edgeportion 883 m and an inner element portion 882 m. FIG. 8 n depicts aJ-clip 884 n comprising a wire crimp 886 n, an edge portion 883 n and aninner element portion 882 n.

Electro-optic mirrors often incorporate a bezel that covers the edge ofthe mirror element and the electrical bus connections. In addition, themirror edge and bus connection are often encapsulated in a pottingmaterial or sealant. As long as the mirror remains functional, theaesthetics of the mirror edge and bus connection are not a concern. Incontrast, Electro-optic mirrors without a bezel typically have both themirror element edge and the associated electrical bus connectionsexposed to the environment. The bus connection typically utilizes ametal member (the term “metal” throughout this discussion on corrosioncan represent a pure metal or a metal alloy) such as a formed clip orstrip. Electro-optic mirrors with bezels often have formed metallicclips or strips made of copper or copper alloy. The appearance andcorrosion resistance of these formed clips or strips become important ifgood aesthetics are to be maintained over the life of the vehicle.Copper and copper alloys tend to corrode and turn green in the salty wetenvironments to which an EC outside mirror is exposed. This is notaesthetically acceptable. Even if the metal bus cannot be vieweddirectly, the formed metal clips or strips are typically made of thinmaterial, usually less than 0.010″ thick and more typically 0.005″ orless in thickness. These thin metal pieces can corrode quickly resultingin structural failure, loss of spring electrical contact force or lossof electrical continuity. This issue can be minimized if the edge of themirror and/or back of the mirror is covered with a paint or coating. Themetal clip could also be protected from the environment with a coatingsuch as a conformal coating, paint or varnish or metal plating orcladding. Examples of suitable conformal coatings are:

1. UV curing epoxy system comprising of 354 bis F resin (Dow Chemical)with 2 percent (by weight) of US-206 (Degussa) and 3 percent (by weight)of UVI-6992 (Union Carbide Corporation—subsidiary of Dow Chemical). 0-3percent (by weight) of US-206 and 2-5 percent (by weight) of UVI-6992.

2. Solvated urethane conformal coating like Humiseal 1A33 (ChaseCorporation, Woodside, N.Y.).

3. Solvated polyisobutylene comprising of 3 parts (by weight) pentaneand 1 part (by weight) Vistanex LM-MS-LC (Exxon Chemical).

Examples of protective metal platings include gold, palladium, rhodium,ruthenium, nickel and silver. In general these coatings or surfaceplatings retard the corrosion and extend the useful life of theelectrical bus; however, corrosion often eventually occurs. Anotherapproach to extending useful bus life is to make the bus clip or stripout of a metal or metal alloy that has good corrosion resistance insalty environments. Suitable metals include the noble metals and noblemetals alloys comprising gold, platinum, iridium, rhodium, ruthenium,palladium and silver as well as metals and metal alloys of titanium,nickel, chromium, molybdenum, tungsten and tantalum including stainlesssteel, Hastalloy C, titanium/aluminum alloys, titanium palladium alloys,titanium ruthenium alloys. Zirconium and its alloys also perform wellunder certain circumstances. A table ranking a number of these metalsand metal alloys after the copper accelerated salt spray (CASS) testingis included herein. The rankings have the following meanings:4—unacceptable corrosion, 3—corrosion evident but acceptable, 2—lightcorrosion evident, and 1—very light/no corrosion.

Corrosion Ranking Table Material Plating Ranking Olin 725 (Cu—Ni—Sn)None 4 Olin 638 (Cu—Al—Si—Co) None 4 Olin 194 (Cu—Fe—P—Zn) None 4 Olin510 Phos. Bronze (Cu—Sn—P) None 4 Olin 713 None 4 Phos. Bronze Tin 4Olin 770 German Silver (Cu—Zn—Ni) None 3 Olin 752 (Cu—Zn—Ni) None 3Monel (Ni—Cu) None 3 Brush Wellman (Cu—Be) None 4 174-10 Palladium 3174-10 Silver 3 174-10 Tin 4 302 Stainless Steel None 2 302 StainlessSteel Tin 3 302 Stainless Steel Silver 3 302 Stainless Steel Rhodium 2302 Stainless Steel Nickel Strike 1 302 Stainless Steel Passivated 2Surface by JS 316 Stainless Steel None 2 Tin Foil None 3 Silver FoilNone 1 Nickel None 1 Titanium Unalloyed (grade 1) None 1 TitaniumUnalloyed (grade 2) None 1 Titanium Unalloyed (grade 4) None 1 Ti—6Al—4V(grade 5) None 1 Ti—3Al—2.5V (grade 9) None 1 Ti—0.15—Pd (grade 11) None1 Ti—0.15Pd (grade 16) None 1 Ti—0.1Ru (grade 26) None 1Ti—3Al—2.5V—0.1Ru (grade 28) None 1 Ti—6Ai—4V—0.1Ru (grade 29) None 1Molybdenum Foil None 2 Gold Foil None 1 Rhodium Foil None 1 Lead FoilNone 3 Tungsten Foil None 1 Palladium Foil None 1 Cobalt Foil None 4Tantalum Foil None 1 Nickel Foil None 1 Nickel Foil Silver 1 316Stainless Steel Tin 3

When the bus interconnection technique incorporates the use of two ormore different metals in close contact with one another, the effects ofgalvanic corrosion are preferably considered. Many interconnectiontechniques utilize conductive adhesives. These adhesives generally areorganic resins such as epoxy, urethane, phenolic, acrylic, silicone orthe like that are embedded with conductive particles such as gold,palladium, nickel, silver, copper, graphite or the like. Unlike a metalsolder joint, organic resins breathe. Moisture, oxygen and other gassescan diffuse through organic resins and cause corrosion. When dissimilarmetals are in contact with one another, this corrosion may beaccelerated by the difference in the electrochemical potential of themetals. Generally, the greater the difference in electrochemicalpotential between the metal, the greater the probability of galvaniccorrosion. It is therefore desirable to minimize the difference inelectrochemical potential between metals selected for use in a bussystem, especially when a naturally non-hermetic electrically conductiveadhesive is used. When one or both of the metals are plated, it ispreferred that a plating material is selected that has anelectrochemical potential in between the electrochemical potentials ofthe two metals. For office environments that are humidity andtemperature controlled, the electrochemical potential differencesbetween the metals are preferably no more than 0.5V. For normalenvironments, the potential difference is preferably no more than 0.25V.For harsh environments, the potential difference is preferably no morethan 0.15V. Many conductive adhesives use silver particulate or flake asthe conductive filler. Silver represents a good compromise between costand nobility. Silver also has excellent conductivity. As described inmetals galvanic compatibility charts such as those supplied by EngineersEdge (www.engineersedge.com) and Laird Technologies (www.lairdtech.com),silver has an anodic index of 0.15V. Tin-plated copper or copper alloythat is typically used for bus connections in bezeled mirrors has ananodic index of 0.65V. When tin plated copper is used in contact withsilver, the large 0.5V anodic potential difference is acceptable for usein controlled office-like environments. The environment associated withoutside vehicular mirrors is by no means a controlled environment. Apotential difference of less than 0.45V is desirable, a difference ofless than 0.25V is preferred and a difference of less than 0.15V is mostpreferred.

Metals Galvanic Compatibility Chart Anodic Metal Surface Index Gold,solid and plated, gold-platinum alloy, graphite carbon 0.00 Rhodiumplated on silver 0.05 Rhodium plating 0.10 Silver, solid or plated; highsilver alloys, monel, high nickel-copper alloys 0.15 Nickel, solid orplated, titanium and s alloys, monel, nickel-copper alloys, titanium0.30 alloys Copper, beryllium copper, cooper; Ni—Cr alloys; austeniticcorrosion-resistant steels; 0.35 most chrome-poly steels; specialtyhigh-temp stainless steels, solid or plated; low brasses or bronzes;silver solder; German silvery high copper-nickel alloys Commercialyellow brass and bronzes 0.40 High brasses and bronzes, naval brass,Muntz metal 0.45 18 percent chromium type corrosion-resistant steels,common 300 series stainless 0.50 steels Chromium plated; tin plated; 12percent chromium type corrosion-resistant steels; 0.60 Most 400 seriesstainless steels Tin-plate; tin-lead solder 0.65 Lead, solid or plated,high lead alloys 0.70 Aluminum, wrought alloys of the 2000 Series 0.75Iron, wrought gray or malleable, plain carbon and low alloy steels;armco iron; cold- 0.85 rolled steel Aluminum, wrought alloys other thanthe 2000 Series aluminum, cast alloys of the 0.90 silicon type; 6000Series aluminum Aluminum, cast alloys other than silicon type, cadmium,plated and chromate 0.95 Hot-dip zinc plate; galvanized steel or electrogalvanized steel 1.20 Zinc, wrought; zinc-base die-casting alloys; zincplated 1.25 Magnesium & magnesium-base alloys, cast or wrought 1.75Beryllium 1.85 High brasses and bronzes, naval brass, Muntz metal 0.4518 percent chromium type corrosion-resistant steels, common 300 seriesstainless 0.50 steels

It should be noted that the potential differences between metalsdepends, at least in part, on the nature of the corrosive environmentthey are measured in. Results measured in, for example, seawater may beslightly different than for fresh water. It should also be noted thatthere can be large differences between passive and active surfaces ofthe same material. The anodic potential of a stainless steel surface maybe substantially reduced by a passivation treatment using nitric acidand/or solutions of oxidizing salts. The anodic potential difference maybe kept within the most preferred 0.15V if silver is used in combinationwith, for example, gold, gold/platinum alloys, platinum, zirconium,carbon graphite, rhodium, nickel, nickel-copper alloys, titanium andmonel. The potential difference may be kept within the preferred 0.25Vwith, for example, beryllium copper, brass, bronze, silver solder,copper, copper-nickel alloys, nickel-chrome alloys, austenitic corrosionresistant steels, and most chrome-moly steels. The potential differencemay be kept within the desired 0.40V by using, for example, 18-8stainless steel or 300 series stainless steel, high brasses and bronzes,naval brass and Muntz metal. When a plating is used, it is desirable tohave the plating material within these anodic potential ranges and mostpreferably have a potential between the two base materials in closecontact with each other. For example, gold, palladium, rhodium,ruthenium, nickel or silver plating generally meets these requirements.The electrical bus is generally connected to the EC mirror drive voltagesource by use of a spade connector or soldered joint. When a solderedjoint or connection is used, the bus metal is preferably solderable.Platings such as gold, palladium, rhodium, ruthenium, nickel, silver andtin can enhance the solderability of the bus clip. For instance, eventhough tin is not a preferred plating, a tin-plated stainless steel busclip solders easily when compared to a plain stainless steel clip. Asolder-friendly, more preferred substrate/plating combination isstainless steel with palladium, silver, nickel or rhodium plating.Stainless steel with a nickel plating followed by a silver, palladium,gold, rhodium or ruthenium plating is a preferred material. Otherpreferred materials include metals or metal alloys comprising tantalum,zirconium, tungsten, and molybdenum with a nickel, silver, gold,palladium, rhodium and ruthenium plating. Other preferred materials aremetals, or metal alloys, comprising titanium or nickel with a nickeland/or silver plating. For enhanced stability, it is desirable topassivate the surface of the base metal.

Turning now to FIGS. 9 a and 9 b, a mirror element comprising a firstsubstrate 912 b and a second substrate 902 b is depicted subsequent tobeing received by a carrier assembly. The carrier assembly comprises asubstantially rigid portion 901 a, 901 b integrated with a pliableperipheral gripping portion 903 a, 903 b. The substantially rigidportion and the pliable peripheral gripping portion may be co-molded,individually molded and adhered to one another, designed to friction fittogether, designed to interference fit together, individually molded andmelted together, or a combination thereof. In any event, the pliableperipheral gripping portion 903 a, 903 b is preferably designed toresult in an interface 909 between the pliable peripheral grippingportion and the perimeter material beyond the crown 913 such that fromnear the crown to near the tip 907 there is a restraining forcegenerated that, at least in part, retains the element proximate thecarrier assembly as desired. An additional adhesion material 905 a, 905b may be utilized to further retain the element proximate the carrierassembly. It should be understood that the perimeter portion 903 a, 903b may be constructed, at least in part, from a material that adheres tothe perimeter material 960 such that the retentive force is alsogenerated along the interface 911 on the rigid portion 901 a, 901 b sideof the crown 903 a, 903 b; in such a case, the perimeter portion 903 a,903 b may extend short of the crown or just beyond the crown as depictedin FIG. 9 b. Preferably, the perimeter portion tip 907 is taperedslightly to provide a visually appealing transition to the elementirrespective of whether the perimeter portion extends beyond the crown.It should be understood that the shape of the perimeter material may bealtered to provide at least one edge substantially parallel to surface915 and the perimeter portion may be designed to impart a morepronounced transition between the crown and the interface 909.

FIG. 9 c depicts an element comprising a first substrate 912 c and asecond substrate 902 c positioned within a carrier 901 c and perimeterportion 903 c. This configuration typically represents the as-moldedcondition of the pliable peripheral gripping portion. FIG. 9 b wouldtypically represent the installed position of the pliable peripheralgripping portion. The installed position allows the pliable peripheralgripping portion to conform to the potential irregularities of the glassprofile. FIG. 9 b is depicting a mechanical interlock between the rigidportion of the carrier and the pliable peripheral gripping portion. Thisis useful for materials that are not intended to be bonded togetherwhether adhered or bonded through a molding process. The mechanicalinterlocks can be spaced around the perimeter of the assembly as needed.FIG. 9 c is depicting a cross-section without a mechanical interlock.Both sections can be used as needed. Another difference between FIGS. 9b and 9 c is the height of the pliable peripheral gripping portion offof the back side of the carrier. FIG. 9 b limits the height off of theback of the carrier of the pliable peripheral gripping portion byplacing some of the pliable peripheral gripping portion between theglass and carrier in place of the heater/foam assembly. This potentiallyeliminates clash conditions inside the housing. FIG. 9 c can be used toallow the heater/foam assembly to be placed to the edge of the glassperimeter. This allows heating of the glass assembly all the way out tothe edge. However, it could potentially create clash conditions of themirror assembly in the mirror housing.

Turning now to FIGS. 9 d-m, various carrier plates are depicted withperimeter gripping portions. FIGS. 9 d-g depict a carrier plate 901 d,901 e, 901 f, 901 g having an integral perimeter gripping portion 903 d,903 e, 903 f, 903 g. In at least one embodiment, the perimeter grippingportion comprises a “goose neck” cross-section shape and comprises aseries of alternating lands 903 d 1, 903 e 1, 903 f 1 and apertures 903d 2, 903 e 2, 903 g 2. The combination of the goose neck shape and thealternating lands and apertures provides hoop stress relief to accountfor differences in expansion coefficients between the element and thecarrier plate/perimeter gripping portion.

FIG. 9 h depicts an element comprising a first substrate 912 h and asecond substrate 902 h held in spaced-apart relationship with respect toone another via a primary seal material 978 h within a carrier plate 901h and perimeter gripping portion 903 h. In this embodiment, theperimeter gripping portion comprises a compressible material that issandwiched between the element and an outer part of the carrier plate toallow for the variations in expansion coefficients between the elementand the carrier plate/perimeter gripping portion.

FIG. 9 i depicts an element comprising a first substrate 912 i and asecond substrate 902 i held in spaced-apart relationship with respect toone another via a primary seal material 978 i within a carrier plate 901i and perimeter gripping portion 903 i. In this embodiment, theperimeter gripping portion comprises a compressible material 904 i thatis sandwiched between the carrier plate and the perimeter grippingportion to allow for the variations in expansion coefficients betweenthe element and the carrier plate/perimeter gripping portion.

FIG. 9 j depicts a carrier plate 901 j having a swivel portion 901 j 1for pivotally attaching a perimeter gripping portion 903 j. The factthat the perimeter gripping portion is allowed to pivot about the swivelportion accounts for variations in expansion coefficients between theelement and the carrier plate/perimeter gripping portion.

FIG. 9 k depicts a carrier plate 901 k having a perimeter grippingportion 903 k. The perimeter gripping portion is preferably molded suchthat it is tilted toward an associated element (not shown). Acompression material 904 k is provided to account for variations inexpansion coefficients between the element and the carrierplate/perimeter gripping portion.

FIG. 91 depicts a carrier plate 901 l having a perimeter grippingportion 903 l. The perimeter gripping portion is preferably molded suchthat it is tilted toward an associated element (not shown). A series ofvertically extending compression elements 904 l are is provided toaccount for variations in expansion coefficients between the element andthe carrier plate/perimeter gripping portion.

FIG. 9 m depicts a carrier plate 901 m having a perimeter grippingportion 903 m. The perimeter gripping portion is preferably molded suchthat it is tilted toward an associated element (not shown). A series ofhorizontally extending compression elements 904 m is provided to accountfor variations in expansion coefficients between the element and thecarrier plate/perimeter gripping portion.

Turning now to FIGS. 10 a-c, an element 1012 a is depicted proximate analignment plate 1001 a, 1001 b and an electrical circuit board 1020 a,1020 b. In at least one embodiment, an electrical clip 1084 a, 1084 bhaving a contact post 1086 a, 1086 c is connected to an elementelectrical connection 1085 a, 1085 b. The element electrical connectionmay be via an electrically conductive epoxy, solder, conductive adhesiveor an edge spring clip. When the element is engaged with the electricalcircuit board, the contact post is received through a hole 1021 a, 1021c in the electrical circuit board and is slidingly engaged with frictionfit contacts 1022 a, 1022 c, 1023 a, 1023 c. FIG. 10 c depicts anenlarged view of the corresponding area 1027 b of FIG. 10 b. In at leastone embodiment, the alignment plate comprises apertures 1003 a, 1004 afor alignment with apertures 1024 b, 1025 b, respectively, of theelectrical circuit board. Preferably, alignment pins (not shown) areprovided elsewhere in the associated mirror assembly, such as, in thehousing or bezel to accurately position the individual components withinthe assembly. In at least one embodiment, the alignment plate comprisesan aperture 1002 a through which the contact post is received foralignment with the corresponding hole in the circuit board. In at leastone embodiment, the alignment plate comprises features 1005 a, 1005 b,1006 a, 1006 b for accurately securing the components within a completeassembly. It should be understood that the electrical circuit board maycomprise components such as a microprocessor and/or other electricalcomponents, such as a display driver, a compass sensor, a temperaturesensor, a moisture detection system, an exterior light control systemand operator interfaces that are at least partially shared with at leastone mirror element dimming circuitry.

It should be understood that the above description and the accompanyingfigures are for illustrative purposes and should in no way be construedas limiting the invention to the particular embodiments shown anddescribed. The appending claims shall be construed to include allequivalents within the scope of the doctrine of equivalents andapplicable patent laws and rules.

1. A variable reflectance mirror element having a periphery area, themirror element comprising: a first optically transparent substrateincluding first and second surfaces; a second substrate including thirdand fourth surfaces and an edge surface adjoining the third and fourthsurfaces, the first and second substrates disposed in a parallel andspaced-apart relationship with the second and third surfaces facing oneanother so as to define a gap therebetween; a first thin-film stackdeposited on the second surface, the first thin-film stack containing anoptical thin-film band circumferentially disposed at a peripheral areaof the second surface; a second thin-film stack covering at least acentral portion of the third surface; and an electrochromic mediumdisposed in the gap, wherein the second thin-film stack includes a leastone electrically conductive layer that is electrically extended over theedge surface to the fourth surface through a conductive section.
 2. Amirror element according to claim 1, wherein the first thin-film stackincludes an optically transparent layer adjoining the optical thin-filmband.
 3. A mirror element according to claim 1, wherein the first andsecond substrates are disposed so as to have at least one edge surfaceof the first substrate misaligned with respect to at least one edgesurface of the second substrate.
 4. A mirror element according to claim2, wherein the optically transparent layer overlays the opticalthin-film band.
 5. A mirror element according to claim 1, wherein theconductive section includes a thin-film coating.
 6. A mirror elementaccording to claim 5, wherein the thin-film coating is deposited ontothe third surface, the edge surface, and the fourth surface of thesecond substrate.
 7. A mirror element according to claim 5, wherein thethin-film coating includes at least a portion of the second thin-filmstack.
 8. A mirror element according to claim 5, wherein the firstthin-film stack is electrically extended to the fourth surface throughan electrically conductive member.
 9. A mirror element according toclaim 8, wherein the electrically conductive member includes a firstclip.
 10. A mirror element according to claim 8, further including anelectrically conductive element is adhered to the fourth surface, theelectrically conductive element being in electrical communication withthe thin-film coating.
 11. A mirror element according to claim 10,wherein a portion of at least one of the electrically conductive elementand the electrically conductive member is encapsulated in at least oneof a potting material and a sealant.
 12. A mirror element according toclaim 10, wherein a portion of at least one of the electricallyconductive element and the electrically conductive member is coated witha conformal coating.
 13. A mirror element according to claim 2, whereinthe intensity of ambient light reflected from the periphery area differsfrom the intensity of light reflected from inside the periphery area byno more than 10 percent.
 14. A mirror element according to claim 13,wherein the intensity of ambient light reflected from the periphery areadiffers from the intensity of light reflected from inside the peripheryarea by no more than 6 percent.
 15. A mirror element according to claim13, wherein the intensity of ambient light reflected from the peripheryarea differs from the intensity of light reflected from inside theperiphery area by no more than 3 percent.
 16. A mirror element accordingto claim 2, wherein a difference in color of ambient light reflectedfrom a periphery area and ambient light reflected from inside theperiphery area is less than 30 C* units.
 17. A mirror element accordingto claim 16, wherein the difference in color is less than 15 C* units.18. A mirror element according to claim 16, wherein the difference incolor is less than 10 C* units.
 19. A mirror element according to claim2, wherein the reflectance of ambient light from the periphery areaexceeds 60 percent.
 20. A variable reflectance mirror element having aperiphery area, the mirror element comprising: a first opticallytransparent substrate including first and second surfaces, a secondsubstrate including third and fourth surfaces and an edge surfaceadjoining the third and fourth surfaces, the first and second substratesdisposed in a parallel and spaced-apart relationship with the second andthird surfaces facing one another so as to define a gap therebetween; afirst thin-film stack deposited on the second surface, the firstthin-film stack containing an optical thin-film band circumferentiallydisposed at a peripheral area of the second surface; a second thin-filmstack covering at least a central portion of the third surface, at leastone of the first and second thin-film stacks including a sequence of afirst transparent oxide layer, at least one metal layer, and a secondtransparent oxide layer; and an electrochromic medium disposed in thegap, wherein the second thin-film stack includes a least oneelectrically conductive layer that is electrically extended over theedge surface to the fourth surface through a conductive section.
 21. Amirror element according to claim 20, wherein the conductive sectionincludes a thin-film coating.
 22. A mirror element according to claim21, wherein the thin film coating includes at least a portion of thesecond thin-film stack.
 23. A mirror element according to claim 21,further including an electrically conductive element adhered to thefourth surface, the electrically conductive element being in electricalcommunication with the thin-film coating.
 24. A mirror element accordingto claim 20, wherein at least one of the first and second oxide layersincludes a transparent conductive oxide.
 25. A variable reflectancemirror element having a periphery area, the mirror element comprising: afirst optically transparent substrate including first and secondsurfaces, a second substrate including third and fourth surfaces and anedge surface adjoining the third and fourth surfaces, the first andsecond substrates disposed in a parallel and spaced-apart relationshipwith the second and third surfaces facing one another so as to define agap therebetween; a first thin-film stack deposited on the secondsurface, the first thin-film stack containing an optical thin-film bandcircumferentially disposed at a peripheral area of the second surface,the first thin-film stack being electrically extended to the fourthsurface through an electrically conductive member; a second thin-filmstack covering at least a central portion of the third surface, whereinthe second thin-film stack includes a least one electrically conductivelayer that is electrically extended over the edge surface to the fourthsurface through a conductive section; an electrochromic medium disposedin the gap; and a conformal coating configured to cover at least aportion of at least one of the conductive section and the electricallyconductive member, the at least a portion being adjacent the fourthsurface.
 26. A mirror element according to claim 25, wherein theconductive section includes a metal plating.
 27. A mirror elementaccording to claim 25, further comprising an electrical bus extendingalong at least a portion of the fourth surface, the electrical bus beingin electrical contact with the conductive section.
 28. A mirror elementaccording to claim 25, wherein the conformal coating includes at leastone of the sealant and potting material.
 29. A mirror element accordingto claim 1 configured as a rearview mirror element for a motor vehicleand further comprising at least one device selected from the groupconsisting of a light source positioned to project light from the secondsubstrate through the first substrate, an interior illuminationassembly, a digital voice processing system, a power supply, a globalpositioning system, an exterior light control, a moisture sensor, aninformation display, a light sensor, a blind spot indicator, a turningsignal indicator, an approach warning, an operator interface, a compass,a temperature indicator, a voice actuated device, a microphone, adimming circuitry, a GPS device, a telecommunication system, anavigation aid, a lane departure warning system, an adaptive cruisecontrol, a vision system, a rear vision system and a tunnel detectionsystem.
 30. A mirror element according to claim 1, wherein the secondthin-film stack includes a layer of chromium adjacent to a layer of aplatinum group metal.